Class: String

Relationships & Source Files
Extension / Inclusion / Inheritance Descendants
Subclasses: Warning::buffer
Super Chains via Extension / Inclusion / Inheritance
Instance Chain: self, `::Comparable`
Inherits:	Object
Defined in:	string.c, complex.c, encoding.c, pack.rb, rational.c, symbol.c, transcode.c, doc/string.rb

Overview

A String object has an arbitrary sequence of bytes, typically representing text or binary data. A String object may be created using .new or as literals.

String objects differ from ::Symbol objects in that ::Symbol objects are designed to be used as identifiers, instead of text or data.

You can create a String object explicitly with:

A string literal.
A heredoc literal.

You can convert certain objects to Strings with:

::Method #String.

Some String methods modify self. Typically, a method whose name ends with ! modifies self and returns self; often, a similarly named method (without the !) returns a new string.

In general, if both bang and non-bang versions of a method exist, the bang method mutates and the non-bang method does not. However, a method without a bang can also mutate, such as #replace.

Substitution Methods

These methods perform substitutions:

#sub: One substitution (or none); returns a new string.
#sub!: One substitution (or none); returns self if any changes, nil otherwise.
#gsub: Zero or more substitutions; returns a new string.
#gsub!: Zero or more substitutions; returns self if any changes, nil otherwise.

Each of these methods takes:

A first argument, pattern (String or ::Regexp), that specifies the substring(s) to be replaced.
Either of the following:
- A second argument, replacement (String or Hash), that determines the replacing string.
- A block that will determine the replacing string.

The examples in this section mostly use the #sub and #gsub methods; the principles illustrated apply to all four substitution methods.

Argument pattern

Argument pattern is commonly a regular expression:

s = 'hello'
s.sub(/[aeiou]/, '*') # => "h*llo"
s.gsub(/[aeiou]/, '*') # => "h*ll*"
s.gsub(/[aeiou]/, '')  # => "hll"
s.sub(/ell/, 'al')     # => "halo"
s.gsub(/xyzzy/, '*')   # => "hello"
'THX1138'.gsub(/\d+/, '00') # => "THX00"

When pattern is a string, all its characters are treated as ordinary characters (not as ::Regexp special characters):

'THX1138'.gsub('\d+', '00') # => "THX1138"

String replacement

If replacement is a string, that string determines the replacing string that is substituted for the matched text.

Each of the examples above uses a simple string as the replacing string.

String replacement may contain back-references to the pattern’s captures:

\n (n is a non-negative integer) refers to $n.
\k<name> refers to the named capture name.

See Regexp for details.

Note that within the string replacement, a character combination such as $& is treated as ordinary text, not as a special match variable. However, you may refer to some special match variables using these combinations:

\& and \0 correspond to $&, which contains the complete matched text.
\' corresponds to $', which contains the string after the match.
\` corresponds to $`, which contains the string before the match.
\+ corresponds to $+, which contains the last capture group.

See Regexp for details.

Note that \\ is interpreted as an escape, i.e., a single backslash.

Note also that a string literal consumes backslashes. See Literals for details about string literals.

A back-reference is typically preceded by an additional backslash. For example, if you want to write a back-reference \& in replacement with a double-quoted string literal, you need to write "..\\&..".

If you want to write a non-back-reference string \& in replacement, you need to first escape the backslash to prevent this method from interpreting it as a back-reference, and then you need to escape the backslashes again to prevent a string literal from consuming them: "..\\\\&..".

You may want to use the block form to avoid excessive backslashes.

Hash replacement

If the argument replacement is a hash, and pattern matches one of its keys, the replacing string is the value for that key:

h = {'foo' => 'bar', 'baz' => 'bat'}
'food'.sub('foo', h) # => "bard"

Note that a symbol key does not match:

h = {foo: 'bar', baz: 'bat'}
'food'.sub('foo', h) # => "d"

Block

In the block form, the current match string is passed to the block; the block’s return value becomes the replacing string:

s = '@'
'1234'.gsub(/\d/) { |match| s.succ! } # => "ABCD"

Special match variables such as $1, $2, $`, $&, and $' are set appropriately.

Whitespace in Strings

In the class String, whitespace is defined as a contiguous sequence of characters consisting of any mixture of the following:

NL (null): "\x00", "\u0000".
HT (horizontal tab): "\x09", "\t".
LF (line feed): "\x0a", "\n".
VT (vertical tab): "\x0b", "\v".
FF (form feed): "\x0c", "\f".
CR (carriage return): "\x0d", "\r".
SP (space): "\x20", " ".

Whitespace is relevant for the following methods:

#lstrip, #lstrip!: Strip leading whitespace.
#rstrip, #rstrip!: Strip trailing whitespace.
#strip, #strip!: Strip leading and trailing whitespace.

What’s Here

First, what’s elsewhere. ::Class String:

Inherits from the {Object class}.
Includes the {Comparable module}.

Here, class String provides methods that are useful for:

Creating a String

.new: Returns a new string.
.try_convert: Returns a new string created from a given object.

Freezing/Unfreezing

#+@: Returns a string that is not frozen: self if not frozen; self.dup otherwise.
#-@ (aliased as #dedup): Returns a string that is frozen: self if already frozen; self.freeze otherwise.
#freeze: Freezes self if not already frozen; returns self.

Querying

Counts

#length (aliased as #size): Returns the count of characters (not bytes).
#empty?: Returns whether the length of self is zero.
#bytesize: Returns the count of bytes.
#count: Returns the count of substrings matching given strings.

Substrings

#=~: Returns the index of the first substring that matches a given Regexp or other object; returns nil if no match is found.
#byteindex: Returns the byte index of the first occurrence of a given substring.
#byterindex: Returns the byte index of the last occurrence of a given substring.
#index: Returns the index of the first occurrence of a given substring; returns nil if none found.
#rindex: Returns the index of the last occurrence of a given substring; returns nil if none found.
#include?: Returns true if the string contains a given substring; false otherwise.
#match: Returns a ::MatchData object if the string matches a given Regexp; nil otherwise.
#match?: Returns true if the string matches a given Regexp; false otherwise.
#start_with?: Returns true if the string begins with any of the given substrings.
#end_with?: Returns true if the string ends with any of the given substrings.

Encodings

#encoding: Returns the ::Encoding object that represents the encoding of the string.
#unicode_normalized?: Returns true if the string is in Unicode normalized form; false otherwise.
#valid_encoding?: Returns true if the string contains only characters that are valid for its encoding.
#ascii_only?: Returns true if the string has only ASCII characters; false otherwise.

Other

#sum: Returns a basic checksum for the string: the sum of each byte.
#hash: Returns the integer hash code.

Comparing

#== (aliased as #===): Returns true if a given other string has the same content as self.
#eql?: Returns true if the content is the same as the given other string.
#<=>: Returns -1, 0, or 1 as a given other string is smaller than, equal to, or larger than self.
#casecmp: Ignoring case, returns -1, 0, or 1 as self is smaller than, equal to, or larger than a given other string.
#casecmp?: Ignoring case, returns whether a given other string is equal to self.

Modifying

Each of these methods modifies self.

Insertion

#insert: Returns self with a given string inserted at a specified offset.
#<<: Returns self concatenated with a given string or integer.
#append_as_bytes: Returns self concatenated with strings without performing any encoding validation or conversion.
#prepend: Prefixes to self the concatenation of given other strings.

Substitution

#bytesplice: Replaces bytes of self with bytes from a given string; returns self.
#sub!: Replaces the first substring that matches a given pattern with a given replacement string; returns self if any changes, nil otherwise.
#gsub!: Replaces each substring that matches a given pattern with a given replacement string; returns self if any changes, nil otherwise.
#succ! (aliased as #next!): Returns self modified to become its own successor.
#replace: Returns self with its entire content replaced by a given string.
#reverse!: Returns self with its characters in reverse order.
#setbyte: Sets the byte at a given integer offset to a given value; returns the argument.
#tr!: Replaces specified characters in self with specified replacement characters; returns self if any changes, nil otherwise.
#tr_s!: Replaces specified characters in self with specified replacement characters, removing duplicates from the substrings that were modified; returns self if any changes, nil otherwise.

Casing

#capitalize!: Upcases the initial character and downcases all others; returns self if any changes, nil otherwise.
#downcase!: Downcases all characters; returns self if any changes, nil otherwise.
#upcase!: Upcases all characters; returns self if any changes, nil otherwise.
#swapcase!: Upcases each downcase character and downcases each upcase character; returns self if any changes, nil otherwise.

Encoding

#encode!: Returns self with all characters transcoded from one encoding to another.
#unicode_normalize!: Unicode-normalizes self; returns self.
#scrub!: Replaces each invalid byte with a given character; returns self.
#force_encoding: Changes the encoding to a given encoding; returns self.

Deletion

#clear: Removes all content, so that self is empty; returns self.
#slice!, #[]=: Removes a substring determined by a given index, start/length, range, regexp, or substring.
#squeeze!: Removes contiguous duplicate characters; returns self.
#delete!: Removes characters as determined by the intersection of substring arguments.
#delete_prefix!: Removes leading prefix; returns self if any changes, nil otherwise.
#delete_suffix!: Removes trailing suffix; returns self if any changes, nil otherwise.
#lstrip!: Removes leading whitespace; returns self if any changes, nil otherwise.
#rstrip!: Removes trailing whitespace; returns self if any changes, nil otherwise.
#strip!: Removes leading and trailing whitespace; returns self if any changes, nil otherwise.
#chomp!: Removes the trailing record separator, if found; returns self if any changes, nil otherwise.
#chop!: Removes trailing newline characters if found; otherwise removes the last character; returns self if any changes, nil otherwise.

Converting to New String

Each of these methods returns a new String based on self, often just a modified copy of self.

Extension

#*: Returns the concatenation of multiple copies of self.
#+: Returns the concatenation of self and a given other string.
#center: Returns a copy of self, centered by specified padding.
#concat: Returns the concatenation of self with given other strings.
#ljust: Returns a copy of self of a given length, right-padded with a given other string.
#rjust: Returns a copy of self of a given length, left-padded with a given other string.

Encoding

#b: Returns a copy of self with ASCII-8BIT encoding.
#scrub: Returns a copy of self with each invalid byte replaced with a given character.
#unicode_normalize: Returns a copy of self with each character Unicode-normalized.
#encode: Returns a copy of self with all characters transcoded from one encoding to another.

Substitution

#dump: Returns a printable version of self, enclosed in double-quotes.
#undump: Returns a copy of self with all \xNN notations replaced by \uNNNN notations and all escaped characters unescaped.
#sub: Returns a copy of self with the first substring matching a given pattern replaced with a given replacement string.
#gsub: Returns a copy of self with each substring that matches a given pattern replaced with a given replacement string.
#succ (aliased as #next): Returns the string that is the successor to self.
#reverse: Returns a copy of self with its characters in reverse order.
#tr: Returns a copy of self with specified characters replaced with specified replacement characters.
#tr_s: Returns a copy of self with specified characters replaced with specified replacement characters, removing duplicates from the substrings that were modified.
#%: Returns the string resulting from formatting a given object into self.

Casing

#capitalize: Returns a copy of self with the first character upcased and all other characters downcased.
#downcase: Returns a copy of self with all characters downcased.
#upcase: Returns a copy of self with all characters upcased.
#swapcase: Returns a copy of self with all upcase characters downcased and all downcase characters upcased.

Deletion

#delete: Returns a copy of self with characters removed.
#delete_prefix: Returns a copy of self with a given prefix removed.
#delete_suffix: Returns a copy of self with a given suffix removed.
#lstrip: Returns a copy of self with leading whitespace removed.
#rstrip: Returns a copy of self with trailing whitespace removed.
#strip: Returns a copy of self with leading and trailing whitespace removed.
#chomp: Returns a copy of self with a trailing record separator removed, if found.
#chop: Returns a copy of self with trailing newline characters or the last character removed.
#squeeze: Returns a copy of self with contiguous duplicate characters removed.
#[] (aliased as #slice): Returns a substring determined by a given index, start/length, range, regexp, or string.
#byteslice: Returns a substring determined by a given index, start/length, or range.
#chr: Returns the first character.

Duplication

#to_s (aliased as #to_str): If self is a subclass of String, returns self copied into a String; otherwise, returns self.

Converting to Non-String

Each of these methods converts the contents of self to a non-String.

Characters, Bytes, and Clusters

#bytes: Returns an array of the bytes in self.
#chars: Returns an array of the characters in self.
#codepoints: Returns an array of the integer ordinals in self.
#getbyte: Returns the integer byte at the given index in self.
#grapheme_clusters: Returns an array of the grapheme clusters in self.

Splitting

#lines: Returns an array of the lines in self, as determined by a given record separator.
#partition: Returns a 3-element array determined by the first substring that matches a given substring or regexp.
#rpartition: Returns a 3-element array determined by the last substring that matches a given substring or regexp.
#split: Returns an array of substrings determined by a given delimiter – regexp or string – or, if a block is given, passes those substrings to the block.

Matching

#scan: Returns an array of substrings matching a given regexp or string, or, if a block is given, passes each matching substring to the block.
#unpack: Returns an array of substrings extracted from self according to a given format.
#unpack1: Returns the first substring extracted from self according to a given format.

Numerics

#hex: Returns the integer value of the leading characters, interpreted as hexadecimal digits.
#oct: Returns the integer value of the leading characters, interpreted as octal digits.
#ord: Returns the integer ordinal of the first character in self.
#to_c: Returns the complex value of leading characters, interpreted as a complex number.
#to_i: Returns the integer value of leading characters, interpreted as an integer.
#to_f: Returns the floating-point value of leading characters, interpreted as a floating-point number.
#to_r: Returns the rational value of leading characters, interpreted as a rational.

Strings and Symbols

#inspect: Returns a copy of self, enclosed in double quotes, with special characters escaped.
#intern (aliased as #to_sym): Returns the symbol corresponding to self.

Iterating

#each_byte: Calls the given block with each successive byte in self.
#each_char: Calls the given block with each successive character in self.
#each_codepoint: Calls the given block with each successive integer codepoint in self.
#each_grapheme_cluster: Calls the given block with each successive grapheme cluster in self.
#each_line: Calls the given block with each successive line in self, as determined by a given record separator.
#upto: Calls the given block with each string value returned by successive calls to #succ.

Class Method Summary

.try_convert(object) ⇒ Object, ...

Attempts to convert the given object to a string.
.new(*args) constructor Internal use only

Instance Attribute Summary

#ascii_only? ⇒ Boolean readonly

Returns whether self contains only ASCII characters:
#empty? ⇒ Boolean readonly

Returns whether the length of self is zero:
#valid_encoding? ⇒ Boolean readonly

Returns true if self is encoded correctly, false otherwise:

Instance Method Summary

#%(object) ⇒ String

Returns the result of formatting object into the format specifications contained in self (see Format Specifications):
#*(n) ⇒ String

Returns a new string containing n copies of self:
#+(other_string) ⇒ String

Returns a new string containing other_string concatenated to self:
#+ ⇒ String, self

Returns self if self is not frozen and can be mutated without warning issuance.
#- ⇒ String (also: #dedup)

Returns a frozen string equal to self.
#<<(object) ⇒ self

Appends a string representation of object to self; returns self.
#<=>(other_string) ⇒ 1, ...

Compares self and other_string, returning:
#==(object) ⇒ Boolean (also: #===)

Returns whether object is equal to self.
#===(object) ⇒ Boolean

Alias for #==.
#=~(object) ⇒ Integer^?

When object is a ::Regexp, returns the index of the first substring in self matched by object, or nil if no match is found; updates Regexp-related global variables:
#[](index) ⇒ String^? (also: #slice)

Returns the substring of self specified by the arguments.
#[]=(index, other_string) ⇒ String

Returns self with all, a substring, or none of its contents replaced; returns the argument other_string.
#append_as_bytes(*objects) ⇒ self

Concatenates each object in objects into self; returns self; performs no encoding validation or conversion:
#b ⇒ String

Returns a copy of self that has ASCII-8BIT encoding; the underlying bytes are not modified:
#byteindex(object, offset = 0) ⇒ Integer^?

Returns the 0-based integer index of a substring of self specified by object (a string or ::Regexp) and offset, or nil if there is no such substring; the returned index is the count of bytes (not characters).
#byterindex(object, offset = self.bytesize) ⇒ Integer^?

Returns the 0-based integer index of a substring of self that is the last match for the given object (a string or ::Regexp) and offset, or nil if there is no such substring; the returned index is the count of bytes (not characters).
#bytes ⇒ array_of_bytes

Returns an array of the bytes in self:
#bytesize ⇒ Integer

Returns the count of bytes in self.
#byteslice(offset, length = 1) ⇒ String^?

Returns a substring of self, or nil if the substring cannot be constructed.
#bytesplice(offset, length, str) ⇒ self

Replaces target bytes in self with source bytes from the given string str; returns self.
#capitalize(mapping = :ascii) ⇒ String

Returns a string containing the characters in self, each with possibly changed case:
#capitalize!(mapping = :ascii) ⇒ self^?

Like #capitalize, except that:
#casecmp(other_string) ⇒ 1, ...

Ignoring case, compares self and other_string; returns:
#casecmp?(other_string) ⇒ true, ...

Returns true if self and other_string are equal after Unicode case folding, false if unequal, nil if incomparable.
#center(size, pad_string = ' ') ⇒ String

Returns a centered copy of self.
#chars ⇒ array_of_characters

Returns an array of the characters in self:
#chomp(line_sep = $/) ⇒ String

Returns a new string copied from self, with trailing characters possibly removed:
#chomp!(line_sep = $/) ⇒ self^?

Like #chomp, except that:
#chop ⇒ String

Returns a new string copied from self, with trailing characters possibly removed.
#chop! ⇒ self^?

Like #chop, except that:
#chr ⇒ String

Returns a string containing the first character of self:
#clear ⇒ self

Removes the contents of self:
#codepoints ⇒ array_of_integers

Returns an array of the codepoints in self; each codepoint is the integer value for a character:
#concat(*objects) ⇒ String

Concatenates each object in objects to self; returns self:
#count(*selectors) ⇒ Integer

Returns the total number of characters in self that are specified by the given selectors.
#crypt(salt_str) ⇒ String

Returns the string generated by calling crypt(3) standard library function with str and salt_str, in this order, as its arguments.
#dedup ⇒ String

Alias for #-@.
#delete(*selectors) ⇒ String

Returns a new string that is a copy of self with certain characters removed; the removed characters are all instances of those specified by the given string selectors.
#delete!(*selectors) ⇒ self^?

Like #delete, but modifies self in place; returns self if any characters were deleted, nil otherwise.
#delete_prefix(prefix) ⇒ String

Returns a copy of self with leading substring prefix removed:
#delete_prefix!(prefix) ⇒ self^?

Like #delete_prefix, except that self is modified in place; returns self if the prefix is removed, nil otherwise.
#delete_suffix(suffix) ⇒ String

Returns a copy of self with trailing substring suffix removed:
#delete_suffix!(suffix) ⇒ self^?

Like #delete_suffix, except that self is modified in place; returns self if the suffix is removed, nil otherwise.
#downcase(mapping) ⇒ String

Returns a new string containing the downcased characters in self:
#downcase!(mapping) ⇒ self^?

Like #downcase, except that:
#dump ⇒ String

Returns a printable version of self, enclosed in double-quotes:
#each_byte {|byte| ... } ⇒ self

With a block given, calls the block with each successive byte from self; returns self:
#each_char {|char| ... } ⇒ self

With a block given, calls the block with each successive character from self; returns self:
#each_codepoint {|codepoint| ... } ⇒ self

With a block given, calls the block with each successive codepoint from self; each codepoint is the integer value for a character; returns self:
#each_grapheme_cluster {|grapheme_cluster| ... } ⇒ self

With a block given, calls the given block with each successive grapheme cluster from self (see Unicode Grapheme Cluster Boundaries); returns self:
#each_line(record_separator = $/, chomp: false) {|substring| ... } ⇒ self

With a block given, forms the substrings (lines) that are the result of splitting self at each occurrence of the given record_separator; passes each line to the block; returns self.
#encode(dst_encoding = Encoding.default_internal, **enc_opts) ⇒ String

Returns a copy of self transcoded as determined by dst_encoding; see Encodings.
#encode!(dst_encoding = Encoding.default_internal, **enc_opts) ⇒ self

Like #encode, but applies encoding changes to self; returns self.
#encoding ⇒ Encoding

Alias for Regexp#encoding.
#end_with?(*strings) ⇒ Boolean

Returns whether self ends with any of the given strings:
#eql?(object) ⇒ Boolean

Returns whether self and object have the same length and content:
#force_encoding(encoding) ⇒ self

Changes the encoding of self to the given #encoding, which may be a string encoding name or an ::Encoding object; does not change the underlying bytes; returns self:
#getbyte(index) ⇒ Integer^?

Returns the byte at zero-based #index as an integer:
#grapheme_clusters ⇒ array_of_grapheme_clusters

Returns an array of the grapheme clusters in self (see Unicode Grapheme Cluster Boundaries):
#gsub(pattern, replacement) ⇒ String

Returns a copy of self with zero or more substrings replaced.
#gsub!(pattern, replacement) ⇒ self^?

Like #gsub, except that:
#hash ⇒ Integer

Returns the integer hash value for self.
#hex ⇒ Integer

Interprets the leading substring of self as hexadecimal, possibly signed; returns its value as an integer.
#include?(other_string) ⇒ Boolean

Returns whether self contains other_string:
#index(pattern, offset = 0) ⇒ Integer^?

Returns the integer position of the first substring that matches the given argument pattern, or nil if none found.
#new(string = ''.encode(Encoding::ASCII_8BIT), **options) ⇒ String constructor

Returns a new String object containing the given string.
#initialize_copy(other_string) ⇒ self

Alias for #replace.
#insert(offset, other_string) ⇒ self

Inserts the given other_string into self; returns self.
#inspect ⇒ String

Returns a printable version of self, enclosed in double-quotes.
#intern ⇒ Symbol (also: #to_sym)

Returns the ::Symbol object derived from self, creating it if it did not already exist:
#length ⇒ Integer (also: #size)

Returns the count of characters (not bytes) in self:
#lines(record_separator = $/, chomp: false) ⇒ String

Returns substrings (“lines”) of self according to the given arguments:
#ljust(width, pad_string = ' ') ⇒ String

Returns a copy of self, left-justified and, if necessary, right-padded with the pad_string:
#lstrip ⇒ String

Returns a copy of self with leading whitespace removed; see Whitespace in Strings:
#lstrip! ⇒ self^?

Like #lstrip, except that:
#match(pattern, offset = 0) ⇒ MatchData^?

Creates a ::MatchData object based on self and the given arguments; updates {Regexp Global Variables}.
#match?(pattern, offset = 0) ⇒ Boolean

Returns whether a match is found for self and the given arguments; does not update {Regexp Global Variables}.
#next ⇒ String (also: #succ)

Returns the successor to self.
#next! ⇒ self (also: #succ!)

Like #succ, but modifies self in place; returns self.
#oct ⇒ Integer

Interprets the leading substring of self as octal, binary, decimal, or hexadecimal, possibly signed; returns their value as an integer.
#ord ⇒ Integer

Returns the integer ordinal of the first character of self:
#partition(pattern) ⇒ Array, ...

Returns a 3-element array of substrings of self.
#prepend(*other_strings) ⇒ String

Prefixes to self the concatenation of the given other_strings; returns self:
#replace(other_string) ⇒ self (also: #initialize_copy)

Replaces the contents of self with the contents of other_string; returns self:
#reverse ⇒ String

Returns a new string with the characters from self in reverse order.
#reverse! ⇒ self

Returns self with its characters reversed:
#rindex(pattern, offset = self.length) ⇒ Integer^?

Returns the integer position of the last substring that matches the given argument pattern, or nil if none found.
#rjust(width, pad_string = ' ') ⇒ String

Returns a right-justified copy of self.
#rpartition(pattern) ⇒ Array, ...

Returns a 3-element array of substrings of self.
#rstrip ⇒ String

Returns a copy of self with trailing whitespace removed; see Whitespace in Strings:
#rstrip! ⇒ self^?

Like #rstrip, except that:
#scan(pattern) ⇒ array_of_results

Matches a pattern against self:
#scrub(replacement_string = default_replacement_string) ⇒ String

Returns a copy of self with each invalid byte sequence replaced by the given replacement_string.
#scrub!(replacement_string = default_replacement_string) ⇒ self

Like #scrub, except that:
#setbyte(index, integer) ⇒ Integer

Sets the byte at zero-based offset #index to the value of the given integer; returns integer:
#size ⇒ Integer

Alias for #length.
#[](index) ⇒ String^?

Alias for #[].
#slice!(index) ⇒ String^?

Like #[] (and its alias #slice), except that:
#split(field_sep = $;, limit = 0) ⇒ String

Creates an array of substrings by splitting self at each occurrence of the given field separator field_sep.
#squeeze(*selectors) ⇒ String

Returns a copy of self with each tuple (doubling, tripling, etc.) of specified characters “squeezed” down to a single character.
#squeeze!(*selectors) ⇒ self^?

Like #squeeze, except that:
#start_with?(*patterns) ⇒ Boolean

Returns whether self starts with any of the given patterns.
#strip ⇒ String

Returns a copy of self with leading and trailing whitespace removed; see Whitespace in Strings:
#strip! ⇒ self^?

Like #strip, except that:
#sub(pattern, replacement) ⇒ String

Returns a copy of self, possibly with a substring replaced.
#sub!(pattern, replacement) ⇒ self^?

Like #sub, except that:
#succ ⇒ String

Alias for #next.
#succ! ⇒ self

Alias for #next!.
#sum(n = 16) ⇒ Integer

Returns a basic n-bit checksum of the characters in self; the checksum is the sum of the binary value of each byte in self, modulo 2**n - 1:
#swapcase(mapping) ⇒ String

Returns a string containing the characters in self, with cases reversed:
#swapcase!(mapping) ⇒ self^?

Like #swapcase, except that:
#to_c ⇒ Complex

Returns a ::Complex object: parses the leading substring of self to extract two numeric values that become the coordinates of the complex object.
#to_f ⇒ Float

Returns the result of interpreting leading characters in self as a ::Float:
#to_i(base = 10) ⇒ Integer

Returns the result of interpreting leading characters in self as an integer in the given base; base must be either 0 or in range (2..36):
#to_r ⇒ Rational

Returns the result of interpreting leading characters in self as a rational value:
#to_s ⇒ self, String (also: #to_str)

Returns self if self is a String, or self converted to a String if self is a subclass of String.
#to_str ⇒ self, String

Alias for #to_s.
#to_sym ⇒ Symbol

Alias for #intern.
#tr(selector, replacements) ⇒ String

Returns a copy of self with each character specified by string selector translated to the corresponding character in string replacements.
#tr!(selector, replacements) ⇒ self^?

Like #tr, but modifies self in place.
#tr_s(selector, replacements) ⇒ String

Like #tr, but also squeezes the modified portions of the translated string; returns a new string (translated and squeezed).
#tr_s!(selector, replacements) ⇒ self^?

Like #tr_s, but modifies self in place.
#undump ⇒ String

Returns an unescaped version of self:
#unicode_normalize(form = :nfc) ⇒ String

Returns a copy of self with Unicode normalization applied.
#unicode_normalize!(form = :nfc) ⇒ self

Like #unicode_normalize, except that the normalization is performed on self.
#unicode_normalized?(form = :nfc) ⇒ Boolean

Returns true if self is in the given form of Unicode normalization, false otherwise.
#unpack(template, offset: 0, &block) ⇒ Array

Extracts data from self.
#unpack1(template, offset: 0) ⇒ Object

Like #unpack, but unpacks and returns only the first extracted object.
#upcase(mapping) ⇒ String

Returns a string containing the upcased characters in self:
#upcase!(mapping) ⇒ self^?

Upcases the characters in self; returns self if any changes were made, nil otherwise:
#upto(other_string, exclusive = false) {|string| ... } ⇒ self

With a block given, calls the block with each String value returned by successive calls to String#succ; the first value is self, the next is self.succ, and so on; the sequence terminates when value other_string is reached; returns self:
#dup Internal use only
#freeze Internal use only

`::Comparable` - Included

#<	Compares two objects based on the receiver’s #<=> method, returning true if it returns a value less than 0.
#<=	Compares two objects based on the receiver’s #<=> method, returning true if it returns a value less than or equal to 0.
#==	Compares two objects based on the receiver’s #<=> method, returning true if it returns 0.
#>	Compares two objects based on the receiver’s #<=> method, returning true if it returns a value greater than 0.
#>=	Compares two objects based on the receiver’s #<=> method, returning true if it returns a value greater than or equal to 0.
#between?	Returns `false` if obj #<=> min is less than zero or if obj #<=> max is greater than zero, `true` otherwise.
#clamp	In `(min, max)` form, returns min if obj #<=> min is less than zero, max if obj #<=> max is greater than zero, and obj otherwise.

Constructor Details

.new(*args)

This method is for internal use only.

[ GitHub ]

# File 'string.c', line 2140


static VALUE
rb_str_s_new(int argc, VALUE *argv, VALUE klass)
{
    if (klass != rb_cString) {
        return rb_class_new_instance_pass_kw(argc, argv, klass);
    }

    static ID keyword_ids[2];
    VALUE orig, opt, encoding = Qnil, capacity = Qnil;
    VALUE kwargs[2];
    rb_encoding *enc = NULL;

    int n = rb_scan_args(argc, argv, "01:", &orig, &opt);
    if (NIL_P(opt)) {
        return rb_class_new_instance_pass_kw(argc, argv, klass);
    }

    keyword_ids[0] = rb_id_encoding();
    CONST_ID(keyword_ids[1], "capacity");
    rb_get_kwargs(opt, keyword_ids, 0, 2, kwargs);
    encoding = kwargs[0];
    capacity = kwargs[1];

    if (n == 1) {
        orig = StringValue(orig);
    }
    else {
        orig = Qnil;
    }

    if (UNDEF_P(encoding)) {
        if (!NIL_P(orig)) {
            encoding = rb_obj_encoding(orig);
        }
    }

    if (!UNDEF_P(encoding)) {
        enc = rb_to_encoding(encoding);
    }

    // If capacity is nil, we're basically just duping `orig`.
    if (UNDEF_P(capacity)) {
        if (NIL_P(orig)) {
            VALUE empty_str = str_new(klass, "", 0);
            if (enc) {
                rb_enc_associate(empty_str, enc);
            }
            return empty_str;
        }
        VALUE copy = str_duplicate(klass, orig);
        rb_enc_associate(copy, enc);
        ENC_CODERANGE_CLEAR(copy);
        return copy;
    }

    long capa = 0;
    capa = NUM2LONG(capacity);
    if (capa < 0) {
        capa = 0;
    }

    if (!NIL_P(orig)) {
        long orig_capa = rb_str_capacity(orig);
        if (orig_capa > capa) {
            capa = orig_capa;
        }
    }

    VALUE str = str_enc_new(klass, NULL, capa, enc);
    STR_SET_LEN(str, 0);
    TERM_FILL(RSTRING_PTR(str), enc ? rb_enc_mbmaxlen(enc) : 1);

    if (!NIL_P(orig)) {
        rb_str_buf_append(str, orig);
    }

    return str;
}

#new(string = ''.encode(Encoding::ASCII_8BIT), **options) ⇒ `String`

Returns a new String object containing the given string.

The options are optional keyword options (see below).

With no argument given and keyword #encoding also not given, returns an empty string with the ::Encoding ASCII-8BIT:

s = String.new # => ""
s.encoding     # => #<Encoding:ASCII-8BIT>

With argument string given and keyword option #encoding not given, returns a new string with the same encoding as string:

s0 = 'foo'.encode(Encoding::UTF_16)
s1 = String.new(s0)
s1.encoding # => #<Encoding:UTF-16 (dummy)>

(Unlike String.new, a string literal like '' or a here document literal always has script encoding.)

With keyword option #encoding given, returns a string with the specified encoding; the #encoding may be an ::Encoding object, an encoding name, or an encoding name alias:

String.new(encoding: Encoding::US_ASCII).encoding        # => #<Encoding:US-ASCII>
String.new('', encoding: Encoding::US_ASCII).encoding    # => #<Encoding:US-ASCII>
String.new('foo', encoding: Encoding::US_ASCII).encoding # => #<Encoding:US-ASCII>
String.new('foo', encoding: 'US-ASCII').encoding         # => #<Encoding:US-ASCII>
String.new('foo', encoding: 'ASCII').encoding            # => #<Encoding:US-ASCII>

The given encoding need not be valid for the string’s content, and its validity is not checked:

s = String.new('こんにちは', encoding: 'ascii')
s.valid_encoding? # => false

But the given #encoding itself is checked:

String.new('foo', encoding: 'bar') # Raises ArgumentError.

With keyword option capacity given, the given value is advisory only, and may or may not set the size of the internal buffer, which may in turn affect performance:

String.new('foo', capacity: 1)    # Buffer size is at least 4 (includes terminal null byte).
String.new('foo', capacity: 4096) # Buffer size is at least 4;
                                  # may be equal to, greater than, or less than 4096.

[ GitHub ]

# File 'string.c', line 2062


static VALUE
rb_str_init(int argc, VALUE *argv, VALUE str)
{
    static ID keyword_ids[2];
    VALUE orig, opt, venc, vcapa;
    VALUE kwargs[2];
    rb_encoding *enc = 0;
    int n;

    if (!keyword_ids[0]) {
        keyword_ids[0] = rb_id_encoding();
        CONST_ID(keyword_ids[1], "capacity");
    }

    n = rb_scan_args(argc, argv, "01:", &orig, &opt);
    if (!NIL_P(opt)) {
        rb_get_kwargs(opt, keyword_ids, 0, 2, kwargs);
        venc = kwargs[0];
        vcapa = kwargs[1];
        if (!UNDEF_P(venc) && !NIL_P(venc)) {
            enc = rb_to_encoding(venc);
        }
        if (!UNDEF_P(vcapa) && !NIL_P(vcapa)) {
            long capa = NUM2LONG(vcapa);
            long len = 0;
            int termlen = enc ? rb_enc_mbminlen(enc) : 1;

            if (capa < STR_BUF_MIN_SIZE) {
                capa = STR_BUF_MIN_SIZE;
            }
            if (n == 1) {
                StringValue(orig);
                len = RSTRING_LEN(orig);
                if (capa < len) {
                    capa = len;
                }
                if (orig == str) n = 0;
            }
            str_modifiable(str);
            if (STR_EMBED_P(str) || FL_TEST(str, STR_SHARED|STR_NOFREE)) {
                /* make noembed always */
                const size_t size = (size_t)capa + termlen;
                const char *const old_ptr = RSTRING_PTR(str);
                const size_t osize = RSTRING_LEN(str) + TERM_LEN(str);
                char *new_ptr = ALLOC_N(char, size);
                if (STR_EMBED_P(str)) RUBY_ASSERT((long)osize <= str_embed_capa(str));
                memcpy(new_ptr, old_ptr, osize < size ? osize : size);
                FL_UNSET_RAW(str, STR_SHARED|STR_NOFREE);
                RSTRING(str)->as.heap.ptr = new_ptr;
            }
            else if (STR_HEAP_SIZE(str) != (size_t)capa + termlen) {
                SIZED_REALLOC_N(RSTRING(str)->as.heap.ptr, char,
                        (size_t)capa + termlen, STR_HEAP_SIZE(str));
            }
            STR_SET_LEN(str, len);
            TERM_FILL(&RSTRING(str)->as.heap.ptr[len], termlen);
            if (n == 1) {
                memcpy(RSTRING(str)->as.heap.ptr, RSTRING_PTR(orig), len);
                rb_enc_cr_str_exact_copy(str, orig);
            }
            FL_SET(str, STR_NOEMBED);
            RSTRING(str)->as.heap.aux.capa = capa;
        }
        else if (n == 1) {
            rb_str_replace(str, orig);
        }
        if (enc) {
            rb_enc_associate(str, enc);
            ENC_CODERANGE_CLEAR(str);
        }
    }
    else if (n == 1) {
        rb_str_replace(str, orig);
    }
    return str;
}

Class Method Details

.try_convert(object) ⇒ Object, ...

Attempts to convert the given object to a string.

If object is already a string, returns object, unmodified.

Otherwise if object responds to :to_str, calls object.to_str and returns the result.

Returns nil if object does not respond to :to_str.

Raises an exception unless object.to_str returns a string.

[ GitHub ]

# File 'string.c', line 2969


static VALUE
rb_str_s_try_convert(VALUE dummy, VALUE str)
{
    return rb_check_string_type(str);
}

Instance Attribute Details

#ascii_only? ⇒ `Boolean` (readonly)

Returns whether self contains only ASCII characters:

'abc'.ascii_only?         # => true
"abc\u{6666}".ascii_only? # => false

Related: see Querying.

[ GitHub ]

# File 'string.c', line 11537


static VALUE
rb_str_is_ascii_only_p(VALUE str)
{
    int cr = rb_enc_str_coderange(str);

    return RBOOL(cr == ENC_CODERANGE_7BIT);
}

#empty? ⇒ `Boolean` (readonly)

Returns whether the length of self is zero:

'hello'.empty? # => false
' '.empty? # => false
''.empty? # => true

Related: see Querying.

[ GitHub ]

# File 'string.c', line 2467


static VALUE
rb_str_empty(VALUE str)
{
    return RBOOL(RSTRING_LEN(str) == 0);
}

#valid_encoding? ⇒ `Boolean` (readonly)

Returns true if self is encoded correctly, false otherwise:

"\xc2\xa1".force_encoding(Encoding::UTF_8).valid_encoding? # => true
"\xc2".force_encoding(Encoding::UTF_8).valid_encoding?     # => false
"\x80".force_encoding(Encoding::UTF_8).valid_encoding?     # => false

[ GitHub ]

# File 'string.c', line 11517


static VALUE
rb_str_valid_encoding_p(VALUE str)
{
    int cr = rb_enc_str_coderange(str);

    return RBOOL(cr != ENC_CODERANGE_BROKEN);
}

Instance Method Details

#%(object) ⇒ `String`

Returns the result of formatting object into the format specifications contained in self (see Format Specifications):

'%05d' % 123 # => "00123"

If self contains multiple format specifications, object must be an array or hash containing the objects to be formatted:

'%-5s: %016x' % [ 'ID', self.object_id ]                # => "ID   : 00002b054ec93168"
'foo = %{foo}' % {foo: 'bar'}                           # => "foo = bar"
'foo = %{foo}, baz = %{baz}' % {foo: 'bar', baz: 'bat'} # => "foo = bar, baz = bat"

Related: see Converting to New String.

[ GitHub ]

# File 'string.c', line 2635


static VALUE
rb_str_format_m(VALUE str, VALUE arg)
{
    VALUE tmp = rb_check_array_type(arg);

    if (!NIL_P(tmp)) {
        return rb_str_format(RARRAY_LENINT(tmp), RARRAY_CONST_PTR(tmp), str);
    }
    return rb_str_format(1, &arg, str);
}

#*(n) ⇒ `String`

Returns a new string containing n copies of self:

'Ho!' * 3 # => "Ho!Ho!Ho!"
'No!' * 0 # => ""

Related: see Converting to New String.

[ GitHub ]

# File 'string.c', line 2557


VALUE
rb_str_times(VALUE str, VALUE times)
{
    VALUE str2;
    long n, len;
    char *ptr2;
    int termlen;

    if (times == INT2FIX(1)) {
        return str_duplicate(rb_cString, str);
    }
    if (times == INT2FIX(0)) {
        str2 = str_alloc_embed(rb_cString, 0);
        rb_enc_copy(str2, str);
        return str2;
    }
    len = NUM2LONG(times);
    if (len < 0) {
        rb_raise(rb_eArgError, "negative argument");
    }
    if (RSTRING_LEN(str) == 1 && RSTRING_PTR(str)[0] == 0) {
        if (STR_EMBEDDABLE_P(len, 1)) {
            str2 = str_alloc_embed(rb_cString, len + 1);
            memset(RSTRING_PTR(str2), 0, len + 1);
        }
        else {
            str2 = str_alloc_heap(rb_cString);
            RSTRING(str2)->as.heap.aux.capa = len;
            RSTRING(str2)->as.heap.ptr = ZALLOC_N(char, (size_t)len + 1);
        }
        STR_SET_LEN(str2, len);
        rb_enc_copy(str2, str);
        return str2;
    }
    if (len && LONG_MAX/len <  RSTRING_LEN(str)) {
        rb_raise(rb_eArgError, "argument too big");
    }

    len *= RSTRING_LEN(str);
    termlen = TERM_LEN(str);
    str2 = str_enc_new(rb_cString, 0, len, STR_ENC_GET(str));
    ptr2 = RSTRING_PTR(str2);
    if (len) {
        n = RSTRING_LEN(str);
        memcpy(ptr2, RSTRING_PTR(str), n);
        while (n <= len/2) {
            memcpy(ptr2 + n, ptr2, n);
            n *= 2;
        }
        memcpy(ptr2 + n, ptr2, len-n);
    }
    STR_SET_LEN(str2, len);
    TERM_FILL(&ptr2[len], termlen);
    rb_enc_cr_str_copy_for_substr(str2, str);

    return str2;
}

#+(other_string) ⇒ `String`

Returns a new string containing other_string concatenated to self:

'Hello from ' + self.to_s # => "Hello from main"

Related: see Converting to New String.

[ GitHub ]

# File 'string.c', line 2484


VALUE
rb_str_plus(VALUE str1, VALUE str2)
{
    VALUE str3;
    rb_encoding *enc;
    char *ptr1, *ptr2, *ptr3;
    long len1, len2;
    int termlen;

    StringValue(str2);
    enc = rb_enc_check_str(str1, str2);
    RSTRING_GETMEM(str1, ptr1, len1);
    RSTRING_GETMEM(str2, ptr2, len2);
    termlen = rb_enc_mbminlen(enc);
    if (len1 > LONG_MAX - len2) {
        rb_raise(rb_eArgError, "string size too big");
    }
    str3 = str_enc_new(rb_cString, 0, len1+len2, enc);
    ptr3 = RSTRING_PTR(str3);
    memcpy(ptr3, ptr1, len1);
    memcpy(ptr3+len1, ptr2, len2);
    TERM_FILL(&ptr3[len1+len2], termlen);

    ENCODING_CODERANGE_SET(str3, rb_enc_to_index(enc),
                           ENC_CODERANGE_AND(ENC_CODERANGE(str1), ENC_CODERANGE(str2)));
    RB_GC_GUARD(str1);
    RB_GC_GUARD(str2);
    return str3;
}

#+ ⇒ `String`, `self`

Returns self if self is not frozen and can be mutated without warning issuance.

Otherwise returns self.dup, which is not frozen.

Related: see Freezing/Unfreezing.

[ GitHub ]

# File 'string.c', line 3298


static VALUE
str_uplus(VALUE str)
{
    if (OBJ_FROZEN(str) || CHILLED_STRING_P(str)) {
        return rb_str_dup(str);
    }
    else {
        return str;
    }
}

#- ⇒ `String` Also known as: #dedup

Returns a frozen string equal to self.

The returned string is self if and only if all of the following are true:

self is already frozen.
self is an instance of String (rather than of a subclass of String)
self has no instance variables set on it.

Otherwise, the returned string is a frozen copy of self.

Returning self, when possible, saves duplicating self; see {Data deduplication}.

It may also save duplicating other, already-existing, strings:

s0 = 'foo'
s1 = 'foo'
s0.object_id == s1.object_id       # => false
(-s0).object_id == (-s1).object_id # => true

Note that method #-@ is convenient for defining a constant:

FileName = -'config/database.yml'

While its alias #dedup is better suited for chaining:

'foo'.dedup.gsub!('o')

Related: see Freezing/Unfreezing.

[ GitHub ]

# File 'string.c', line 3343


static VALUE
str_uminus(VALUE str)
{
    if (!BARE_STRING_P(str) && !rb_obj_frozen_p(str)) {
        str = rb_str_dup(str);
    }
    return rb_fstring(str);
}

#<<(object) ⇒ `self`

Appends a string representation of object to self; returns self.

If object is a string, appends it to self:

s = 'foo'
s << 'bar' # => "foobar"
s          # => "foobar"

If object is an integer, its value is considered a codepoint; converts the value to a character before concatenating:

s = 'foo'
s << 33 # => "foo!"

Additionally, if the codepoint is in range 0..0xff and the encoding of self is Encoding::US_ASCII, changes the encoding to Encoding::ASCII_8BIT:

s = 'foo'.encode(Encoding::US_ASCII)
s.encoding # => #<Encoding:US-ASCII>
s << 0xff  # => "foo\xFF"
s.encoding # => #<Encoding:BINARY (ASCII-8BIT)>

Raises RangeError if that codepoint is not representable in the encoding of self:

s = 'foo'
s.encoding              # => <Encoding:UTF-8>
s << 0x00110000         # 1114112 out of char range (RangeError)
s = 'foo'.encode(Encoding::EUC_JP)
s << 0x00800080         # invalid codepoint 0x800080 in EUC-JP (RangeError)

Related: see Modifying.

[ GitHub ]

# File 'string.c', line 4031


VALUE
rb_str_concat(VALUE str1, VALUE str2)
{
    unsigned int code;
    rb_encoding *enc = STR_ENC_GET(str1);
    int encidx;

    if (RB_INTEGER_TYPE_P(str2)) {
        if (rb_num_to_uint(str2, &code) == 0) {
        }
        else if (FIXNUM_P(str2)) {
            rb_raise(rb_eRangeError, "%ld out of char range", FIX2LONG(str2));
        }
        else {
            rb_raise(rb_eRangeError, "bignum out of char range");
        }
    }
    else {
        return rb_str_append(str1, str2);
    }

    encidx = rb_ascii8bit_appendable_encoding_index(enc, code);

    if (encidx >= 0) {
        rb_str_buf_cat_byte(str1, (unsigned char)code);
    }
    else {
        long pos = RSTRING_LEN(str1);
        int cr = ENC_CODERANGE(str1);
        int len;
        char *buf;

        switch (len = rb_enc_codelen(code, enc)) {
          case ONIGERR_INVALID_CODE_POINT_VALUE:
            rb_raise(rb_eRangeError, "invalid codepoint 0x%X in %s", code, rb_enc_name(enc));
            break;
          case ONIGERR_TOO_BIG_WIDE_CHAR_VALUE:
          case 0:
            rb_raise(rb_eRangeError, "%u out of char range", code);
            break;
        }
        buf = ALLOCA_N(char, len + 1);
        rb_enc_mbcput(code, buf, enc);
        if (rb_enc_precise_mbclen(buf, buf + len + 1, enc) != len) {
            rb_raise(rb_eRangeError, "invalid codepoint 0x%X in %s", code, rb_enc_name(enc));
        }
        rb_str_resize(str1, pos+len);
        memcpy(RSTRING_PTR(str1) + pos, buf, len);
        if (cr == ENC_CODERANGE_7BIT && code > 127) {
            cr = ENC_CODERANGE_VALID;
        }
        else if (cr == ENC_CODERANGE_BROKEN) {
            cr = ENC_CODERANGE_UNKNOWN;
        }
        ENC_CODERANGE_SET(str1, cr);
    }
    return str1;
}

#<=>(other_string) ⇒ `1`, ...

Compares self and other_string, returning:

-1 if other_string is larger.
0 if the two are equal.
1 if other_string is smaller.
nil if the two are incomparable.

Examples:

'foo' <=> 'foo'  # => 0
'foo' <=> 'food' # => -1
'food' <=> 'foo' # => 1
'FOO' <=> 'foo'  # => -1
'foo' <=> 'FOO'  # => 1
'foo' <=> 1      # => nil

Related: see Comparing.

[ GitHub ]

# File 'string.c', line 4316


static VALUE
rb_str_cmp_m(VALUE str1, VALUE str2)
{
    int result;
    VALUE s = rb_check_string_type(str2);
    if (NIL_P(s)) {
        return rb_invcmp(str1, str2);
    }
    result = rb_str_cmp(str1, s);
    return INT2FIX(result);
}

#==(object) ⇒ `Boolean` Also known as: #===

Returns whether object is equal to self.

When object is a string, returns whether object has the same length and content as self:

s = 'foo'
s == 'foo'  # => true
s == 'food' # => false
s == 'FOO'  # => false

Returns false if the two strings’ encodings are not compatible:

"\u{e4 f6 fc}".encode(Encoding::ISO_8859_1) == ("\u{c4 d6 dc}") # => false

When object is not a string:

If object responds to method #to_str, object == self is called and its return value is returned.
If object does not respond to #to_str, false is returned.

Related: Comparing.

[ GitHub ]

# File 'string.c', line 4264


VALUE
rb_str_equal(VALUE str1, VALUE str2)
{
    if (str1 == str2) return Qtrue;
    if (!RB_TYPE_P(str2, T_STRING)) {
        if (!rb_respond_to(str2, idTo_str)) {
            return Qfalse;
        }
        return rb_equal(str2, str1);
    }
    return rb_str_eql_internal(str1, str2);
}

#==(object) ⇒ `Boolean` #===(object) ⇒ `Boolean`

Alias for #==.

#=~(object) ⇒ Integer^?

When object is a ::Regexp, returns the index of the first substring in self matched by object, or nil if no match is found; updates Regexp-related global variables:

'foo' =~ /f/ # => 0
$~           # => #<MatchData "f">
'foo' =~ /o/ # => 1
$~           # => #<MatchData "o">
'foo' =~ /x/ # => nil
$~           # => nil

Note that string =~ regexp is different from regexp =~ string (see Regexp#=~):

number = nil
'no. 9' =~ /(?<number>\d+)/ # => 4
number                      # => nil # Not assigned.
/(?<number>\d+)/ =~ 'no. 9' # => 4
number                      # => "9" # Assigned.

If object is not a ::Regexp, returns the value returned by object =~ self.

Related: see Querying.

[ GitHub ]

# File 'string.c', line 5034


static VALUE
rb_str_match(VALUE x, VALUE y)
{
    switch (OBJ_BUILTIN_TYPE(y)) {
      case T_STRING:
        rb_raise(rb_eTypeError, "type mismatch: String given");

      case T_REGEXP:
        return rb_reg_match(y, x);

      default:
        return rb_funcall(y, idEqTilde, 1, x);
    }
}

#[](index) ⇒ `String`^? #[](start, length) ⇒ `String`^? #[](range) ⇒ `String`^? #[](substring) ⇒ `String`^?
Also known as: #slice

Returns the substring of self specified by the arguments.

Form self[index]

With non-negative integer argument #index given, returns the 1-character substring found in self at character offset index:

'hello'[0]    # => "h"
'hello'[4]    # => "o"
'hello'[5]    # => nil
'тест'[2]     # => "с"
'こんにちは'[4] # => "は"

With negative integer argument #index given, counts backward from the end of self:

'hello'[-1] # => "o"
'hello'[-5] # => "h"
'hello'[-6] # => nil

Form self[start, length]

With integer arguments start and #length given, returns a substring of size #length characters (as available) beginning at character offset specified by start.

If argument start is non-negative, the offset is start:

'hello'[0, 1]  # => "h"
'hello'[0, 5]  # => "hello"
'hello'[0, 6]  # => "hello"
'hello'[2, 3]  # => "llo"
'hello'[2, 0]  # => ""
'hello'[2, -1] # => nil

If argument start is negative, counts backward from the end of self:

'hello'[-1, 1] # => "o"
'hello'[-5, 5] # => "hello"
'hello'[-1, 0] # => ""
'hello'[-6, 5] # => nil

Special case: if start equals the length of self, returns a new empty string:

'hello'[5, 3]  # => ""

Form self[range]

With Range argument range given, forms substring self[range.start, range.size]:

'hello'[0..2]  # => "hel"
'hello'[0, 3]  # => "hel"

'hello'[0...2] # => "he"
'hello'[0, 2]  # => "he"

'hello'[0, 0]  # => ""
'hello'[0...0] # => ""

Form self[regexp, capture = 0]

With Regexp argument regexp given and capture as zero, searches for a matching substring in self; updates Regexp-related global variables:

'hello'[/ell/]     # => "ell"
'hello'[/l+/]      # => "ll"
'hello'[//]        # => ""
'hello'[/nosuch/]  # => nil

With capture as a positive integer n, returns the nth matched group:

'hello'[/(h)(e)(l+)(o)/]    # => "hello"
'hello'[/(h)(e)(l+)(o)/, 1] # => "h"
$1                          # => "h"
'hello'[/(h)(e)(l+)(o)/, 2] # => "e"
$2                          # => "e"
'hello'[/(h)(e)(l+)(o)/, 3] # => "ll"
'hello'[/(h)(e)(l+)(o)/, 4] # => "o"
'hello'[/(h)(e)(l+)(o)/, 5] # => nil

Form self[substring]

With string argument substring given, returns the matching substring of self, if found:

'hello'['ell']      # => "ell"
'hello'['']         # => ""
'hello'['nosuch']   # => nil
'тест'['ес']        # => "ес"
'こんにちは'['んにち'] # => "んにち"

Related: see Converting to New String.

[ GitHub ]

# File 'string.c', line 5743


static VALUE
rb_str_aref_m(int argc, VALUE *argv, VALUE str)
{
    if (argc == 2) {
        if (RB_TYPE_P(argv[0], T_REGEXP)) {
            return rb_str_subpat(str, argv[0], argv[1]);
        }
        else {
            return rb_str_substr_two_fixnums(str, argv[0], argv[1], TRUE);
        }
    }
    rb_check_arity(argc, 1, 2);
    return rb_str_aref(str, argv[0]);
}

#[]=(index, other_string) ⇒ `String` #[]=(start, length, other_string) ⇒ `String` #[]=(range, other_string) ⇒ `String` #[]=(substring, other_string) ⇒ `String`

Returns self with all, a substring, or none of its contents replaced; returns the argument other_string.

Form self[index] = other_string

With non-negative integer argument #index given, searches for the 1-character substring found in self at character offset index:

s = 'hello'
s[0] = 'foo' # => "foo"
s            # => "fooello"

s = 'hello'
s[4] = 'foo' # => "foo"
s            # => "hellfoo"

s = 'hello'
s[5] = 'foo' # => "foo"
s            # => "hellofoo"

s = 'hello'
s[6] = 'foo' # Raises IndexError: index 6 out of string.

With negative integer argument #index given, counts backward from the end of self:

s = 'hello'
s[-1] = 'foo'  # => "foo"
s              # => "hellfoo"

s = 'hello'
s[-5] = 'foo'  # => "foo"
s              # => "fooello"

s = 'hello'
s[-6] = 'foo'  # Raises IndexError: index -6 out of string.

Form self[start, length] = other_string

With integer arguments start and #length given, searches for a substring of size #length characters (as available) beginning at character offset specified by start.

If argument start is non-negative, the offset is +start’:

s = 'hello'
s[0, 1] = 'foo'  # => "foo"
s                # => "fooello"

s = 'hello'
s[0, 5] = 'foo'  # => "foo"
s                # => "foo"

s = 'hello'
s[0, 9] = 'foo'  # => "foo"
s                # => "foo"

s = 'hello'
s[2, 0] = 'foo'  # => "foo"
s                # => "hefoollo"

s = 'hello'
s[2, -1] = 'foo' # Raises IndexError: negative length -1.

If argument start is negative, counts backward from the end of self:

s = 'hello'
s[-1, 1] = 'foo' # => "foo"
s                # => "hellfoo"

s = 'hello'
s[-1, 9] = 'foo' # => "foo"
s                # => "hellfoo"

s = 'hello'
s[-5, 2] = 'foo' # => "foo"
s                # => "foollo"

s = 'hello'
s[-3, 0] = 'foo' # => "foo"
s                # => "hefoollo"

s = 'hello'
s[-6, 2] = 'foo' # Raises IndexError: index -6 out of string.

Special case: if start equals the length of self, the argument is appended to self:

s = 'hello'
s[5, 3] = 'foo' # => "foo"
s               # => "hellofoo"

Form self[range] = other_string

With Range argument range given, equivalent to self[range.start, range.size] = other_string:

s0 = 'hello'
s1 = 'hello'
s0[0..2] = 'foo' # => "foo"
s1[0, 3] = 'foo' # => "foo"
s0               # => "foolo"
s1               # => "foolo"

s = 'hello'
s[0...2] = 'foo' # => "foo"
s                # => "foollo"

s = 'hello'
s[0...0] = 'foo' # => "foo"
s                # => "foohello"

s = 'hello'
s[9..10] = 'foo' # Raises RangeError: 9..10 out of range

Form self[regexp, capture = 0] = other_string

With Regexp argument regexp given and capture as zero, searches for a matching substring in self; updates Regexp-related global variables:

s = 'hello'
s[/l/] = 'L'       # => "L"
[$`, $&, $']       # => ["he", "l", "lo"]
s[/eLlo/] = 'owdy' # => "owdy"
[$`, $&, $']       # => ["h", "eLlo", ""]
s[/eLlo/] = 'owdy' # Raises IndexError: regexp not matched.
[$`, $&, $']       # => [nil, nil, nil]

With capture as a positive integer n, searches for the nth matched group:

s = 'hello'
s[/(h)(e)(l+)(o)/] = 'foo'    # => "foo"
[$`, $&, $']                  # => ["", "hello", ""]

s = 'hello'
s[/(h)(e)(l+)(o)/, 1] = 'foo' # => "foo"
s                             # => "fooello"
[$`, $&, $']                  # => ["", "hello", ""]

s = 'hello'
s[/(h)(e)(l+)(o)/, 2] = 'foo' # => "foo"
s                             # => "hfoollo"
[$`, $&, $']                  # => ["", "hello", ""]

s = 'hello'
s[/(h)(e)(l+)(o)/, 4] = 'foo' # => "foo"
s                             # => "hellfoo"
[$`, $&, $']                  # => ["", "hello", ""]

s = 'hello'
# => "hello"
s[/(h)(e)(l+)(o)/, 5] = 'foo  # Raises IndexError: index 5 out of regexp.

s = 'hello'
s[/nosuch/] = 'foo'           # Raises IndexError: regexp not matched.

Form self[substring] = other_string

With string argument substring given:

s = 'hello'
s['l'] = 'foo'  # => "foo"
s  # => "hefoolo"

s = 'hello'
s['ll'] = 'foo'  # => "foo"
s  # => "hefooo"

s = 'тест'
s['ес'] = 'foo'  # => "foo"
s  # => "тfooт"

s = 'こんにちは'
s['んにち'] = 'foo'  # => "foo"
s  # => "こfooは"

s['nosuch'] = 'foo' # Raises IndexError: string not matched.

Related: see Modifying.

[ GitHub ]

# File 'string.c', line 5964


static VALUE
rb_str_aset_m(int argc, VALUE *argv, VALUE str)
{
    if (argc == 3) {
        if (RB_TYPE_P(argv[0], T_REGEXP)) {
            rb_str_subpat_set(str, argv[0], argv[1], argv[2]);
        }
        else {
            rb_str_update(str, NUM2LONG(argv[0]), NUM2LONG(argv[1]), argv[2]);
        }
        return argv[2];
    }
    rb_check_arity(argc, 2, 3);
    return rb_str_aset(str, argv[0], argv[1]);
}

#append_as_bytes(*objects) ⇒ `self`

Concatenates each object in objects into self; returns self; performs no encoding validation or conversion:

s = 'foo'
s.append_as_bytes(" \xE2\x82") # => "foo \xE2\x82"
s.valid_encoding?              # => false
s.append_as_bytes("\xAC 12")
s.valid_encoding?              # => true

When a given object is an integer, the value is considered an 8-bit byte; if the integer occupies more than one byte (i.e,. is greater than 255), appends only the low-order byte (similar to #setbyte):

s = ""
s.append_as_bytes(0, 257) # => "\u0000\u0001"
s.bytesize                # => 2

Related: see Modifying.

[ GitHub ]

# File 'string.c', line 3880


VALUE
rb_str_append_as_bytes(int argc, VALUE *argv, VALUE str)
{
    long needed_capacity = 0;
    volatile VALUE t0;
    enum ruby_value_type *types = ALLOCV_N(enum ruby_value_type, t0, argc);

    for (int index = 0; index < argc; index++) {
        VALUE obj = argv[index];
        enum ruby_value_type type = types[index] = rb_type(obj);
        switch (type) {
          case T_FIXNUM:
          case T_BIGNUM:
            needed_capacity++;
            break;
          case T_STRING:
            needed_capacity += RSTRING_LEN(obj);
            break;
          default:
            rb_raise(
                rb_eTypeError,
                "wrong argument type %"PRIsVALUE" (expected String or Integer)",
                rb_obj_class(obj)
            );
            break;
        }
    }

    str_ensure_available_capa(str, needed_capacity);
    char *sptr = RSTRING_END(str);

    for (int index = 0; index < argc; index++) {
        VALUE obj = argv[index];
        enum ruby_value_type type = types[index];
        switch (type) {
          case T_FIXNUM:
          case T_BIGNUM: {
            argv[index] = obj = rb_int_and(obj, INT2FIX(0xff));
            char byte = (char)(NUM2INT(obj) & 0xFF);
            *sptr = byte;
            sptr++;
            break;
          }
          case T_STRING: {
            const char *ptr;
            long len;
            RSTRING_GETMEM(obj, ptr, len);
            memcpy(sptr, ptr, len);
            sptr += len;
            break;
          }
          default:
            rb_bug("append_as_bytes arguments should have been validated");
        }
    }

    STR_SET_LEN(str, RSTRING_LEN(str) + needed_capacity);
    TERM_FILL(sptr, TERM_LEN(str)); /* sentinel */

    int cr = ENC_CODERANGE(str);
    switch (cr) {
      case ENC_CODERANGE_7BIT: {
        for (int index = 0; index < argc; index++) {
            VALUE obj = argv[index];
            enum ruby_value_type type = types[index];
            switch (type) {
              case T_FIXNUM:
              case T_BIGNUM: {
                if (!ISASCII(NUM2INT(obj))) {
                    goto clear_cr;
                }
                break;
              }
              case T_STRING: {
                if (ENC_CODERANGE(obj) != ENC_CODERANGE_7BIT) {
                    goto clear_cr;
                }
                break;
              }
              default:
                rb_bug("append_as_bytes arguments should have been validated");
            }
        }
        break;
      }
      case ENC_CODERANGE_VALID:
        if (ENCODING_GET_INLINED(str) == ENCINDEX_ASCII_8BIT) {
            goto keep_cr;
        }
        else {
            goto clear_cr;
        }
        break;
      default:
        goto clear_cr;
        break;
    }

    RB_GC_GUARD(t0);

  clear_cr:
    // If no fast path was hit, we clear the coderange.
    // append_as_bytes is predominently meant to be used in
    // buffering situation, hence it's likely the coderange
    // will never be scanned, so it's not worth spending time
    // precomputing the coderange except for simple and common
    // situations.
    ENC_CODERANGE_CLEAR(str);
  keep_cr:
    return str;
}

#b ⇒ `String`

Returns a copy of self that has ASCII-8BIT encoding; the underlying bytes are not modified:

s = "\x99"
s.encoding   # => #<Encoding:UTF-8>
t = s.b      # => "\x99"
t.encoding   # => #<Encoding:ASCII-8BIT>

s = "\u4095" # => "䂕"
s.encoding   # => #<Encoding:UTF-8>
s.bytes      # => [228, 130, 149]
t = s.b      # => "\xE4\x82\x95"
t.encoding   # => #<Encoding:ASCII-8BIT>
t.bytes      # => [228, 130, 149]

Related: see Converting to New String.

[ GitHub ]

# File 'string.c', line 11473


static VALUE
rb_str_b(VALUE str)
{
    VALUE str2;
    if (STR_EMBED_P(str)) {
        str2 = str_alloc_embed(rb_cString, RSTRING_LEN(str) + TERM_LEN(str));
    }
    else {
        str2 = str_alloc_heap(rb_cString);
    }
    str_replace_shared_without_enc(str2, str);

    if (rb_enc_asciicompat(STR_ENC_GET(str))) {
        // BINARY strings can never be broken; they're either 7-bit ASCII or VALID.
        // If we know the receiver's code range then we know the result's code range.
        int cr = ENC_CODERANGE(str);
        switch (cr) {
          case ENC_CODERANGE_7BIT:
            ENC_CODERANGE_SET(str2, ENC_CODERANGE_7BIT);
            break;
          case ENC_CODERANGE_BROKEN:
          case ENC_CODERANGE_VALID:
            ENC_CODERANGE_SET(str2, ENC_CODERANGE_VALID);
            break;
          default:
            ENC_CODERANGE_CLEAR(str2);
            break;
        }
    }

    return str2;
}

#byteindex(object, offset = 0) ⇒ Integer^?

Returns the 0-based integer index of a substring of self specified by object (a string or ::Regexp) and offset, or nil if there is no such substring; the returned index is the count of bytes (not characters).

When object is a string, returns the index of the first found substring equal to object:

s = 'foo'          # => "foo"
s.size             # => 3 # Three 1-byte characters.
s.bytesize         # => 3 # Three bytes.
s.byteindex('f')   # => 0
s.byteindex('o')   # => 1
s.byteindex('oo')  # => 1
s.byteindex('ooo') # => nil

When object is a ::Regexp, returns the index of the first found substring matching object; updates Regexp-related global variables:

s = 'foo'
s.byteindex(/f/)   # => 0
$~                 # => #<MatchData "f">
s.byteindex(/o/)   # => 1
s.byteindex(/oo/)  # => 1
s.byteindex(/ooo/) # => nil
$~                 # => nil

Integer argument offset, if given, specifies the 0-based index of the byte where searching is to begin.

When offset is non-negative, searching begins at byte position offset:

s = 'foo'
s.byteindex('o', 1) # => 1
s.byteindex('o', 2) # => 2
s.byteindex('o', 3) # => nil

When offset is negative, counts backward from the end of self:

s = 'foo'
s.byteindex('o', -1) # => 2
s.byteindex('o', -2) # => 1
s.byteindex('o', -3) # => 1
s.byteindex('o', -4) # => nil

Raises IndexError if the byte at offset is not the first byte of a character:

s = "\uFFFF\uFFFF"       # => "\uFFFF\uFFFF"
s.size                   # => 2 # Two 3-byte characters.
s.bytesize               # => 6 # Six bytes.
s.byteindex("\uFFFF")    # => 0
s.byteindex("\uFFFF", 1) # Raises IndexError
s.byteindex("\uFFFF", 2) # Raises IndexError
s.byteindex("\uFFFF", 3) # => 3
s.byteindex("\uFFFF", 4) # Raises IndexError
s.byteindex("\uFFFF", 5) # Raises IndexError
s.byteindex("\uFFFF", 6) # => nil

Related: see Querying.

[ GitHub ]

# File 'string.c', line 4674


static VALUE
rb_str_byteindex_m(int argc, VALUE *argv, VALUE str)
{
    VALUE sub;
    VALUE initpos;
    long pos;

    if (rb_scan_args(argc, argv, "11", &sub, &initpos) == 2) {
        long slen = RSTRING_LEN(str);
        pos = NUM2LONG(initpos);
        if (pos < 0 ? (pos += slen) < 0 : pos > slen) {
            if (RB_TYPE_P(sub, T_REGEXP)) {
                rb_backref_set(Qnil);
            }
            return Qnil;
        }
    }
    else {
        pos = 0;
    }

    str_ensure_byte_pos(str, pos);

    if (RB_TYPE_P(sub, T_REGEXP)) {
        if (rb_reg_search(sub, str, pos, 0) >= 0) {
            VALUE match = rb_backref_get();
            struct re_registers *regs = RMATCH_REGS(match);
            pos = BEG(0);
            return LONG2NUM(pos);
        }
    }
    else {
        StringValue(sub);
        pos = rb_str_byteindex(str, sub, pos);
        if (pos >= 0) return LONG2NUM(pos);
    }
    return Qnil;
}

#byterindex(object, offset = self.bytesize) ⇒ Integer^?

Returns the 0-based integer index of a substring of self that is the last match for the given object (a string or ::Regexp) and offset, or nil if there is no such substring; the returned index is the count of bytes (not characters).

When object is a string, returns the index of the last found substring equal to object:

s = 'foo'           # => "foo"
s.size              # => 3 # Three 1-byte characters.
s.bytesize          # => 3 # Three bytes.
s.byterindex('f')   # => 0
  s.byterindex('o')   # => 2
  s.byterindex('oo')  # => 1
  s.byterindex('ooo') # => nil

When object is a ::Regexp, returns the index of the last found substring matching object; updates Regexp-related global variables:

s = 'foo'
s.byterindex(/f/)   # => 0
$~                  # => #<MatchData "f">
s.byterindex(/o/)   # => 2
s.byterindex(/oo/)  # => 1
s.byterindex(/ooo/) # => nil
$~                  # => nil

The last match means starting at the possible last position, not the last of the longest matches:

s = 'foo'
s.byterindex(/o+/) # => 2
$~                 #=> #<MatchData "o">

To get the last longest match, use a negative lookbehind:

s = 'foo'
s.byterindex(/(?<!o)o+/) # => 1
$~                       # => #<MatchData "oo">

Or use method #byteindex with negative lookahead:

s = 'foo'
s.byteindex(/o+(?!.*o)/) # => 1
$~                       #=> #<MatchData "oo">

Integer argument offset, if given, specifies the 0-based index of the byte where searching is to end.

When offset is non-negative, searching ends at byte position offset:

s = 'foo'
s.byterindex('o', 0) # => nil
s.byterindex('o', 1) # => 1
s.byterindex('o', 2) # => 2
s.byterindex('o', 3) # => 2

When offset is negative, counts backward from the end of self:

s = 'foo'
s.byterindex('o', -1) # => 2
s.byterindex('o', -2) # => 1
s.byterindex('o', -3) # => nil

Raises IndexError if the byte at offset is not the first byte of a character:

s = "\uFFFF\uFFFF"        # => "\uFFFF\uFFFF"
s.size                    # => 2 # Two 3-byte characters.
s.bytesize                # => 6 # Six bytes.
s.byterindex("\uFFFF")    # => 3
s.byterindex("\uFFFF", 1) # Raises IndexError
s.byterindex("\uFFFF", 2) # Raises IndexError
s.byterindex("\uFFFF", 3) # => 3
s.byterindex("\uFFFF", 4) # Raises IndexError
s.byterindex("\uFFFF", 5) # Raises IndexError
s.byterindex("\uFFFF", 6) # => nil

Related: see Querying.

[ GitHub ]

# File 'string.c', line 4964


static VALUE
rb_str_byterindex_m(int argc, VALUE *argv, VALUE str)
{
    VALUE sub;
    VALUE initpos;
    long pos, len = RSTRING_LEN(str);

    if (rb_scan_args(argc, argv, "11", &sub, &initpos) == 2) {
        pos = NUM2LONG(initpos);
        if (pos < 0 && (pos += len) < 0) {
            if (RB_TYPE_P(sub, T_REGEXP)) {
                rb_backref_set(Qnil);
            }
            return Qnil;
        }
        if (pos > len) pos = len;
    }
    else {
        pos = len;
    }

    str_ensure_byte_pos(str, pos);

    if (RB_TYPE_P(sub, T_REGEXP)) {
        if (rb_reg_search(sub, str, pos, 1) >= 0) {
            VALUE match = rb_backref_get();
            struct re_registers *regs = RMATCH_REGS(match);
            pos = BEG(0);
            return LONG2NUM(pos);
        }
    }
    else {
        StringValue(sub);
        pos = rb_str_byterindex(str, sub, pos);
        if (pos >= 0) return LONG2NUM(pos);
    }
    return Qnil;
}

#bytes ⇒ `array_of_bytes`

Returns an array of the bytes in self:

'hello'.bytes # => [104, 101, 108, 108, 111]
'тест'.bytes  # => [209, 130, 208, 181, 209, 129, 209, 130]
'こんにちは'.bytes
# => [227, 129, 147, 227, 130, 147, 227, 129, 171, 227, 129, 161, 227, 129, 175]

Related: see Converting to Non-String.

[ GitHub ]

# File 'string.c', line 9698


static VALUE
rb_str_bytes(VALUE str)
{
    VALUE ary = WANTARRAY("bytes", RSTRING_LEN(str));
    return rb_str_enumerate_bytes(str, ary);
}

#bytesize ⇒ Integer

Returns the count of bytes in self.

Note that the byte count may be different from the character count (returned by #size):

s = 'foo'
s.bytesize # => 3
s.size     # => 3
s = 'тест'
s.bytesize # => 8
s.size     # => 4
s = 'こんにちは'
s.bytesize # => 15
s.size     # => 5

Related: see Querying.

[ GitHub ]

# File 'string.c', line 2448


VALUE
rb_str_bytesize(VALUE str)
{
    return LONG2NUM(RSTRING_LEN(str));
}

#byteslice(offset, length = 1) ⇒ `String`^? #byteslice(range) ⇒ `String`^?

Returns a substring of self, or nil if the substring cannot be constructed.

With integer arguments offset and #length given, returns the substring beginning at the given offset and of the given #length (as available):

s = '0123456789'   # => "0123456789"
s.byteslice(2)     # => "2"
s.byteslice(200)   # => nil
s.byteslice(4, 3)  # => "456"
s.byteslice(4, 30) # => "456789"

Returns nil if #length is negative or offset falls outside of self:

s.byteslice(4, -1) # => nil
s.byteslice(40, 2) # => nil

Counts backwards from the end of self if offset is negative:

s = '0123456789'   # => "0123456789"
s.byteslice(-4)    # => "6"
s.byteslice(-4, 3) # => "678"

With Range argument range given, returns byteslice(range.begin, range.size):

s = '0123456789'    # => "0123456789"
s.byteslice(4..6)   # => "456"
s.byteslice(-6..-4) # => "456"
s.byteslice(5..2)   # => "" # range.size is zero.
s.byteslice(40..42) # => nil

The starting and ending offsets need not be on character boundaries:

s = 'こんにちは'
s.byteslice(0, 3) # => "こ"
s.byteslice(1, 3) # => "\x81\x93\xE3"

The encodings of self and the returned substring are always the same:

s.encoding                 # => #<Encoding:UTF-8>
s.byteslice(0, 3).encoding # => #<Encoding:UTF-8>
s.byteslice(1, 3).encoding # => #<Encoding:UTF-8>

But, depending on the character boundaries, the encoding of the returned substring may not be valid:

s.valid_encoding?                 # => true
s.byteslice(0, 3).valid_encoding? # => true
s.byteslice(1, 3).valid_encoding? # => false

Related: see Converting to New String.

[ GitHub ]

# File 'string.c', line 6783


static VALUE
rb_str_byteslice(int argc, VALUE *argv, VALUE str)
{
    if (argc == 2) {
        long beg = NUM2LONG(argv[0]);
        long len = NUM2LONG(argv[1]);
        return str_byte_substr(str, beg, len, TRUE);
    }
    rb_check_arity(argc, 1, 2);
    return str_byte_aref(str, argv[0]);
}

#bytesplice(offset, length, str) ⇒ `self` #bytesplice(offset, length, str, str_offset, str_length) ⇒ `self` #bytesplice(range, str) ⇒ `self` #bytesplice(range, str, str_range) ⇒ `self`

Replaces target bytes in self with source bytes from the given string str; returns self.

In the first form, arguments offset and #length determine the target bytes, and the source bytes are all of the given str:

'0123456789'.bytesplice(0, 3, 'abc')  # => "abc3456789"
'0123456789'.bytesplice(3, 3, 'abc')  # => "012abc6789"
'0123456789'.bytesplice(0, 50, 'abc') # => "abc"
'0123456789'.bytesplice(50, 3, 'abc') # Raises IndexError.

The counts of the target bytes and source source bytes may be different:

'0123456789'.bytesplice(0, 6, 'abc') # => "abc6789"      # Shorter source.
'0123456789'.bytesplice(0, 1, 'abc') # => "abc123456789" # Shorter target.

And either count may be zero (i.e., specifying an empty string):

'0123456789'.bytesplice(0, 3, '')    # => "3456789"       # Empty source.
'0123456789'.bytesplice(0, 0, 'abc') # => "abc0123456789" # Empty target.

In the second form, just as in the first, arugments offset and #length determine the target bytes; argument str contains the source bytes, and the additional arguments str_offset and str_length determine the actual source bytes:

'0123456789'.bytesplice(0, 3, 'abc', 0, 3) # => "abc3456789"
'0123456789'.bytesplice(0, 3, 'abc', 1, 1) # => "b3456789"      # Shorter source.
'0123456789'.bytesplice(0, 1, 'abc', 0, 3) # => "abc123456789"  # Shorter target.
'0123456789'.bytesplice(0, 3, 'abc', 1, 0) # => "3456789"       # Empty source.
'0123456789'.bytesplice(0, 0, 'abc', 0, 3) # => "abc0123456789" # Empty target.

In the third form, argument range determines the target bytes and the source bytes are all of the given str:

'0123456789'.bytesplice(0..2, 'abc')  # => "abc3456789"
'0123456789'.bytesplice(3..5, 'abc')  # => "012abc6789"
'0123456789'.bytesplice(0..5, 'abc')  # => "abc6789"       # Shorter source.
'0123456789'.bytesplice(0..0, 'abc')  # => "abc123456789"  # Shorter target.
'0123456789'.bytesplice(0..2, '')     # => "3456789"       # Empty source.
'0123456789'.bytesplice(0...0, 'abc') # => "abc0123456789" # Empty target.

In the fourth form, just as in the third, arugment range determines the target bytes; argument str contains the source bytes, and the additional argument str_range determines the actual source bytes:

'0123456789'.bytesplice(0..2, 'abc', 0..2)  # => "abc3456789"
'0123456789'.bytesplice(3..5, 'abc', 0..2)  # => "012abc6789"
'0123456789'.bytesplice(0..2, 'abc', 0..1)  # => "ab3456789"     # Shorter source.
'0123456789'.bytesplice(0..1, 'abc', 0..2)  # => "abc23456789"   # Shorter target.
'0123456789'.bytesplice(0..2, 'abc', 0...0) # => "3456789"       # Empty source.
'0123456789'.bytesplice(0...0, 'abc', 0..2) # => "abc0123456789" # Empty target.

In any of the forms, the beginnings and endings of both source and target must be on character boundaries.

In these examples, self has five 3-byte characters, and so has character boundaries at offsets 0, 3, 6, 9, 12, and 15.

'こんにちは'.bytesplice(0, 3, 'abc') # => "abcんにちは"
'こんにちは'.bytesplice(1, 3, 'abc') # Raises IndexError.
'こんにちは'.bytesplice(0, 2, 'abc') # Raises IndexError.

[ GitHub ]

# File 'string.c', line 6828


static VALUE
rb_str_bytesplice(int argc, VALUE *argv, VALUE str)
{
    long beg, len, vbeg, vlen;
    VALUE val;
    int cr;

    rb_check_arity(argc, 2, 5);
    if (!(argc == 2 || argc == 3 || argc == 5)) {
        rb_raise(rb_eArgError, "wrong number of arguments (given %d, expected 2, 3, or 5)", argc);
    }
    if (argc == 2 || (argc == 3 && !RB_INTEGER_TYPE_P(argv[0]))) {
        if (!rb_range_beg_len(argv[0], &beg, &len, RSTRING_LEN(str), 2)) {
            rb_raise(rb_eTypeError, "wrong argument type %s (expected Range)",
                     rb_builtin_class_name(argv[0]));
        }
        val = argv[1];
        StringValue(val);
        if (argc == 2) {
            /* bytesplice(range, str) */
            vbeg = 0;
            vlen = RSTRING_LEN(val);
        }
        else {
            /* bytesplice(range, str, str_range) */
            if (!rb_range_beg_len(argv[2], &vbeg, &vlen, RSTRING_LEN(val), 2)) {
                rb_raise(rb_eTypeError, "wrong argument type %s (expected Range)",
                         rb_builtin_class_name(argv[2]));
            }
        }
    }
    else {
        beg = NUM2LONG(argv[0]);
        len = NUM2LONG(argv[1]);
        val = argv[2];
        StringValue(val);
        if (argc == 3) {
            /* bytesplice(index, length, str) */
            vbeg = 0;
            vlen = RSTRING_LEN(val);
        }
        else {
            /* bytesplice(index, length, str, str_index, str_length) */
            vbeg = NUM2LONG(argv[3]);
            vlen = NUM2LONG(argv[4]);
        }
    }
    str_check_beg_len(str, &beg, &len);
    str_check_beg_len(val, &vbeg, &vlen);
    str_modify_keep_cr(str);

    if (RB_UNLIKELY(ENCODING_GET_INLINED(str) != ENCODING_GET_INLINED(val))) {
        rb_enc_associate(str, rb_enc_check(str, val));
    }

    rb_str_update_1(str, beg, len, val, vbeg, vlen);
    cr = ENC_CODERANGE_AND(ENC_CODERANGE(str), ENC_CODERANGE(val));
    if (cr != ENC_CODERANGE_BROKEN)
        ENC_CODERANGE_SET(str, cr);
    return str;
}

#capitalize(mapping = :ascii) ⇒ `String`

Returns a string containing the characters in self, each with possibly changed case:

The first character is upcased.
All other characters are downcased.

Examples:

'hello world'.capitalize # => "Hello world"
'HELLO WORLD'.capitalize # => "Hello world"

Some characters do not have upcase and downcase, and so are not changed; see Case Mapping:

'1, 2, 3, ...'.capitalize # => "1, 2, 3, ..."

The casing is affected by the given mapping, which may be :ascii, :fold, or :turkic; see Case Mappings.

Related: see Converting to New String.

[ GitHub ]

# File 'string.c', line 8192


static VALUE
rb_str_capitalize(int argc, VALUE *argv, VALUE str)
{
    rb_encoding *enc;
    OnigCaseFoldType flags = ONIGENC_CASE_UPCASE | ONIGENC_CASE_TITLECASE;
    VALUE ret;

    flags = check_case_options(argc, argv, flags);
    enc = str_true_enc(str);
    if (RSTRING_LEN(str) == 0 || !RSTRING_PTR(str)) return str;
    if (flags&ONIGENC_CASE_ASCII_ONLY) {
        ret = rb_str_new(0, RSTRING_LEN(str));
        rb_str_ascii_casemap(str, ret, &flags, enc);
    }
    else {
        ret = rb_str_casemap(str, &flags, enc);
    }
    return ret;
}

#capitalize!(mapping = :ascii) ⇒ `self`^?

Like #capitalize, except that:

Changes character casings in self (not in a copy of self).
Returns self if any changes are made, nil otherwise.

Related: See Modifying.

[ GitHub ]

# File 'string.c', line 8145


static VALUE
rb_str_capitalize_bang(int argc, VALUE *argv, VALUE str)
{
    rb_encoding *enc;
    OnigCaseFoldType flags = ONIGENC_CASE_UPCASE | ONIGENC_CASE_TITLECASE;

    flags = check_case_options(argc, argv, flags);
    str_modify_keep_cr(str);
    enc = str_true_enc(str);
    if (RSTRING_LEN(str) == 0 || !RSTRING_PTR(str)) return Qnil;
    if (flags&ONIGENC_CASE_ASCII_ONLY)
        rb_str_ascii_casemap(str, str, &flags, enc);
    else
        str_shared_replace(str, rb_str_casemap(str, &flags, enc));

    if (ONIGENC_CASE_MODIFIED&flags) return str;
    return Qnil;
}

#casecmp(other_string) ⇒ `1`, ...

Ignoring case, compares self and other_string; returns:

-1 if self.downcase is smaller than other_string.downcase.
0 if the two are equal.
1 if self.downcase is larger than other_string.downcase.
nil if the two are incomparable.

See Case Mapping.

Examples:

'foo'.casecmp('goo')  # => -1
'goo'.casecmp('foo')  # => 1
'foo'.casecmp('food') # => -1
'food'.casecmp('foo') # => 1
'FOO'.casecmp('foo')  # => 0
'foo'.casecmp('FOO')  # => 0
'foo'.casecmp(1)      # => nil

Related: see Comparing.

[ GitHub ]

# File 'string.c', line 4357


static VALUE
rb_str_casecmp(VALUE str1, VALUE str2)
{
    VALUE s = rb_check_string_type(str2);
    if (NIL_P(s)) {
        return Qnil;
    }
    return str_casecmp(str1, s);
}

#casecmp?(other_string) ⇒ `true`, ...

Returns true if self and other_string are equal after Unicode case folding, false if unequal, nil if incomparable.

See Case Mapping.

Examples:

'foo'.casecmp?('goo')  # => false
'goo'.casecmp?('foo')  # => false
'foo'.casecmp?('food') # => false
'food'.casecmp?('foo') # => false
'FOO'.casecmp?('foo')  # => true
'foo'.casecmp?('FOO')  # => true
'foo'.casecmp?(1)      # => nil

Related: see Comparing.

[ GitHub ]

# File 'string.c', line 4446


static VALUE
rb_str_casecmp_p(VALUE str1, VALUE str2)
{
    VALUE s = rb_check_string_type(str2);
    if (NIL_P(s)) {
        return Qnil;
    }
    return str_casecmp_p(str1, s);
}

#center(size, pad_string = ' ') ⇒ `String`

Returns a centered copy of self.

If integer argument #size is greater than the size (in characters) of self, returns a new string of length #size that is a copy of self, centered and padded on one or both ends with pad_string:

'hello'.center(6)             # => "hello "               # Padded on one end.
'hello'.center(10)            # => "  hello   "           # Padded on both ends.
'hello'.center(20, '-|')      # => "-|-|-|-hello-|-|-|-|" # Some padding repeated.
'hello'.center(10, 'abcdefg') # => "abhelloabc"           # Some padding not used.
'  hello  '.center(13)        # => "    hello    "
'тест'.center(10)             # => "   тест   "
'こんにちは'.center(10)         # => "  こんにちは   "      # Multi-byte characters.

If #size is less than or equal to the size of self, returns an unpadded copy of self:

'hello'.center(5)   # => "hello"
'hello'.center(-10) # => "hello"

Related: see Converting to New String.

[ GitHub ]

# File 'string.c', line 11076


static VALUE
rb_str_center(int argc, VALUE *argv, VALUE str)
{
    return rb_str_justify(argc, argv, str, 'c');
}

#chars ⇒ `array_of_characters`

Returns an array of the characters in self:

'hello'.chars     # => ["h", "e", "l", "l", "o"]
'тест'.chars      # => ["т", "е", "с", "т"]
'こんにちは'.chars # => ["こ", "ん", "に", "ち", "は"]
''.chars          # => []

Related: see Converting to Non-String.

[ GitHub ]

# File 'string.c', line 9767


static VALUE
rb_str_chars(VALUE str)
{
    VALUE ary = WANTARRAY("chars", rb_str_strlen(str));
    return rb_str_enumerate_chars(str, ary);
}

#chomp(line_sep = $/) ⇒ `String`

Returns a new string copied from self, with trailing characters possibly removed:

When line_sep is "\n", removes the last one or two characters if they are "\r", "\n", or "\r\n" (but not "\n\r"):

$/                    # => "\n"
"abc\r".chomp         # => "abc"
"abc\n".chomp         # => "abc"
"abc\r\n".chomp       # => "abc"
"abc\n\r".chomp       # => "abc\n"
"тест\r\n".chomp      # => "тест"
"こんにちは\r\n".chomp  # => "こんにちは"

When line_sep is '' (an empty string), removes multiple trailing occurrences of "\n" or "\r\n" (but not "\r" or "\n\r"):

"abc\n\n\n".chomp('')           # => "abc"
"abc\r\n\r\n\r\n".chomp('')     # => "abc"
"abc\n\n\r\n\r\n\n\n".chomp('') # => "abc"
"abc\n\r\n\r\n\r".chomp('')     # => "abc\n\r\n\r\n\r"
"abc\r\r\r".chomp('')           # => "abc\r\r\r"

When line_sep is neither "\n" nor '', removes a single trailing line separator if there is one:

'abcd'.chomp('cd')   # => "ab"
'abcdcd'.chomp('cd') # => "abcd"
'abcd'.chomp('xx')   # => "abcd"

Related: see Converting to New String.

[ GitHub ]

# File 'string.c', line 10236


static VALUE
rb_str_chomp(int argc, VALUE *argv, VALUE str)
{
    VALUE rs = chomp_rs(argc, argv);
    if (NIL_P(rs)) return str_duplicate(rb_cString, str);
    return rb_str_subseq(str, 0, chompped_length(str, rs));
}

#chomp!(line_sep = $/) ⇒ `self`^?

Like #chomp, except that:

Removes trailing characters from self (not from a copy of self).
Returns self if any characters are removed, nil otherwise.

Related: see Modifying.

[ GitHub ]

# File 'string.c', line 10216


static VALUE
rb_str_chomp_bang(int argc, VALUE *argv, VALUE str)
{
    VALUE rs;
    str_modifiable(str);
    if (RSTRING_LEN(str) == 0 && argc < 2) return Qnil;
    rs = chomp_rs(argc, argv);
    if (NIL_P(rs)) return Qnil;
    return rb_str_chomp_string(str, rs);
}

#chop ⇒ `String`

Returns a new string copied from self, with trailing characters possibly removed.

Removes "\r\n" if those are the last two characters.

"abc\r\n".chop      # => "abc"
"тест\r\n".chop     # => "тест"
"こんにちは\r\n".chop # => "こんにちは"

Otherwise removes the last character if it exists.

'abcd'.chop     # => "abc"
'тест'.chop     # => "тес"
'こんにちは'.chop # => "こんにち"
''.chop         # => ""

If you only need to remove the newline separator at the end of the string, #chomp is a better alternative.

Related: see Converting to New String.

[ GitHub ]

# File 'string.c', line 10060


static VALUE
rb_str_chop(VALUE str)
{
    return rb_str_subseq(str, 0, chopped_length(str));
}

#chop! ⇒ `self`^?

Like #chop, except that:

Removes trailing characters from self (not from a copy of self).
Returns self if any characters are removed, nil otherwise.

Related: see Modifying.

[ GitHub ]

# File 'string.c', line 10034


static VALUE
rb_str_chop_bang(VALUE str)
{
    str_modify_keep_cr(str);
    if (RSTRING_LEN(str) > 0) {
        long len;
        len = chopped_length(str);
        STR_SET_LEN(str, len);
        TERM_FILL(&RSTRING_PTR(str)[len], TERM_LEN(str));
        if (ENC_CODERANGE(str) != ENC_CODERANGE_7BIT) {
            ENC_CODERANGE_CLEAR(str);
        }
        return str;
    }
    return Qnil;
}

#chr ⇒ `String`

Returns a string containing the first character of self:

'hello'.chr     # => "h"
'тест'.chr      # => "т"
'こんにちは'.chr # => "こ"
''.chr          # => ""

Related: see Converting to New String.

[ GitHub ]

# File 'string.c', line 6609


static VALUE
rb_str_chr(VALUE str)
{
    return rb_str_substr(str, 0, 1);
}

#clear ⇒ `self`

Removes the contents of self:

s = 'foo'
s.clear # => ""
s       # => ""

Related: see Modifying.

[ GitHub ]

# File 'string.c', line 6587


static VALUE
rb_str_clear(VALUE str)
{
    str_discard(str);
    STR_SET_EMBED(str);
    STR_SET_LEN(str, 0);
    RSTRING_PTR(str)[0] = 0;
    if (rb_enc_asciicompat(STR_ENC_GET(str)))
        ENC_CODERANGE_SET(str, ENC_CODERANGE_7BIT);
    else
        ENC_CODERANGE_SET(str, ENC_CODERANGE_VALID);
    return str;
}

#codepoints ⇒ `array_of_integers`

Returns an array of the codepoints in self; each codepoint is the integer value for a character:

'hello'.codepoints     # => [104, 101, 108, 108, 111]
'тест'.codepoints      # => [1090, 1077, 1089, 1090]
'こんにちは'.codepoints # => [12371, 12435, 12395, 12385, 12399]
''.codepoints          # => []

Related: see Converting to Non-String.

[ GitHub ]

# File 'string.c', line 9827


static VALUE
rb_str_codepoints(VALUE str)
{
    VALUE ary = WANTARRAY("codepoints", rb_str_strlen(str));
    return rb_str_enumerate_codepoints(str, ary);
}

#concat(*objects) ⇒ `String`

Concatenates each object in objects to self; returns self:

'foo'.concat('bar', 'baz') # => "foobarbaz"

For each given object object that is an integer, the value is considered a codepoint and converted to a character before concatenation:

'foo'.concat(32, 'bar', 32, 'baz') # => "foo bar baz" # Embeds spaces.
'те'.concat(1089, 1090)            # => "тест"
'こん'.concat(12395, 12385, 12399)  # => "こんにちは"

Related: see Converting to New String.

[ GitHub ]

# File 'string.c', line 3834


static VALUE
rb_str_concat_multi(int argc, VALUE *argv, VALUE str)
{
    str_modifiable(str);

    if (argc == 1) {
        return rb_str_concat(str, argv[0]);
    }
    else if (argc > 1) {
        int i;
        VALUE arg_str = rb_str_tmp_new(0);
        rb_enc_copy(arg_str, str);
        for (i = 0; i < argc; i++) {
            rb_str_concat(arg_str, argv[i]);
        }
        rb_str_buf_append(str, arg_str);
    }

    return str;
}

#count(*selectors) ⇒ Integer

Returns the total number of characters in self that are specified by the given selectors.

For one 1-character selector, returns the count of instances of that character:

s = 'abracadabra'
s.count('a') # => 5
s.count('b') # => 2
s.count('x') # => 0
s.count('')  # => 0

s = 'тест'
s.count('т')  # => 2
s.count('е')  # => 1

s = 'よろしくお願いします'
s.count('よ')  # => 1
s.count('し')  # => 2

For one multi-character selector, returns the count of instances for all specified characters:

s = 'abracadabra'
s.count('ab')     # => 7
s.count('abc')    # => 8
s.count('abcd')   # => 9
s.count('abcdr')  # => 11
s.count('abcdrx') # => 11

Order and repetition do not matter:

s.count('ba')   == s.count('ab') # => true
s.count('baab') == s.count('ab') # => true

For multiple selectors, forms a single selector that is the intersection of characters in all selectors and returns the count of instances for that selector:

s = 'abcdefg'
s.count('abcde', 'dcbfg') == s.count('bcd') # => true
s.count('abc', 'def')     == s.count('')    # => true

In a character selector, three characters get special treatment:

A caret ('^') functions as a negation operator for the immediately following characters:
```
s = 'abracadabra'
s.count('^bc') # => 8  # Count of all except 'b' and 'c'.
```

A hyphen ('-') between two other characters defines a range of characters:

s = 'abracadabra'
s.count('a-c') # => 8  # Count of all 'a', 'b', and 'c'.

A backslash ('\') acts as an escape for a caret, a hyphen, or another backslash:

s = 'abracadabra'
s.count('\^bc')           # => 3  # Count of '^', 'b', and 'c'.
s.count('a\-c')           # => 6  # Count of 'a', '-', and 'c'.
'foo\bar\baz'.count('\\') # => 2  # Count of '\'.

These usages may be mixed:

s = 'abracadabra'
s.count('a-cq-t') # => 10  # Multiple ranges.
s.count('ac-d')   # => 7   # Range mixed with plain characters.
s.count('^a-c')   # => 3   # Range mixed with negation.

For multiple selectors, all forms may be used, including negations, ranges, and escapes.

s = 'abracadabra'
s.count('^abc', '^def') == s.count('^abcdef') # => true
s.count('a-e', 'c-g')   == s.count('cde')     # => true
s.count('^abc', 'c-g')  == s.count('defg')    # => true

Related: see Querying.

[ GitHub ]

# File 'string.c', line 8993


static VALUE
rb_str_count(int argc, VALUE *argv, VALUE str)
{
    char table[TR_TABLE_SIZE];
    rb_encoding *enc = 0;
    VALUE del = 0, nodel = 0, tstr;
    char *s, *send;
    int i;
    int ascompat;
    size_t n = 0;

    rb_check_arity(argc, 1, UNLIMITED_ARGUMENTS);

    tstr = argv[0];
    StringValue(tstr);
    enc = rb_enc_check(str, tstr);
    if (argc == 1) {
        const char *ptstr;
        if (RSTRING_LEN(tstr) == 1 && rb_enc_asciicompat(enc) &&
            (ptstr = RSTRING_PTR(tstr),
             ONIGENC_IS_ALLOWED_REVERSE_MATCH(enc, (const unsigned char *)ptstr, (const unsigned char *)ptstr+1)) &&
            !is_broken_string(str)) {
            int clen;
            unsigned char c = rb_enc_codepoint_len(ptstr, ptstr+1, &clen, enc);

            s = RSTRING_PTR(str);
            if (!s || RSTRING_LEN(str) == 0) return INT2FIX(0);
            send = RSTRING_END(str);
            while (s < send) {
                if (*(unsigned char*)s++ == c) n++;
            }
            return SIZET2NUM(n);
        }
    }

    tr_setup_table(tstr, table, TRUE, &del, &nodel, enc);
    for (i=1; i<argc; i++) {
        tstr = argv[i];
        StringValue(tstr);
        enc = rb_enc_check(str, tstr);
        tr_setup_table(tstr, table, FALSE, &del, &nodel, enc);
    }

    s = RSTRING_PTR(str);
    if (!s || RSTRING_LEN(str) == 0) return INT2FIX(0);
    send = RSTRING_END(str);
    ascompat = rb_enc_asciicompat(enc);
    while (s < send) {
        unsigned int c;

        if (ascompat && (c = *(unsigned char*)s) < 0x80) {
            if (table[c]) {
                n++;
            }
            s++;
        }
        else {
            int clen;
            c = rb_enc_codepoint_len(s, send, &clen, enc);
            if (tr_find(c, table, del, nodel)) {
                n++;
            }
            s += clen;
        }
    }

    return SIZET2NUM(n);
}

#crypt(salt_str) ⇒ `String`

Returns the string generated by calling crypt(3) standard library function with str and salt_str, in this order, as its arguments. Please do not use this method any longer. It is legacy; provided only for backward compatibility with ruby scripts in earlier days. It is bad to use in contemporary programs for several reasons:

Behaviour of C’s crypt(3) depends on the OS it is run. The generated string lacks data portability.
On some OSes such as Mac OS, crypt(3) never fails (i.e. silently ends up in unexpected results).
On some OSes such as Mac OS, crypt(3) is not thread safe.
So-called “traditional” usage of crypt(3) is very very very weak. According to its manpage, Linux’s traditional crypt(3) output has only 2**56 variations; too easy to brute force today. And this is the default behaviour.
In order to make things robust some OSes implement so-called “modular” usage. To go through, you have to do a complex build-up of the salt_str parameter, by hand. Failure in generation of a proper salt string tends not to yield any errors; typos in parameters are normally not detectable.
- For instance, in the following example, the second invocation of String#crypt is wrong; it has a typo in “round=” (lacks “s”). However the call does not fail and something unexpected is generated.
```
"foo".crypt("$5$rounds=1000$salt$") # OK, proper usage
"foo".crypt("$5$round=1000$salt$")  # Typo not detected
```
Even in the “modular” mode, some hash functions are considered archaic and no longer recommended at all; for instance module $1$ is officially abandoned by its author: see

phk.freebsd.dk/sagas/md5crypt_eol/ . For another

instance module <code>$3$</code> is considered completely
broken: see the manpage of FreeBSD.

On some OS such as Mac OS, there is no modular mode. Yet, as written above, crypt(3) on Mac OS never fails. This means even if you build up a proper salt string it generates a traditional DES hash anyways, and there is no way for you to be aware of.
```
"foo".crypt("$5$rounds=1000$salt$") # => "$5fNPQMxC5j6."
```

If for some reason you cannot migrate to other secure contemporary password hashing algorithms, install the string-crypt gem and require 'string/crypt' to continue using it.

[ GitHub ]

# File 'string.c', line 10799


static VALUE
rb_str_crypt(VALUE str, VALUE salt)
{
#ifdef HAVE_CRYPT_R
    VALUE databuf;
    struct crypt_data *data;
#   define CRYPT_END() ALLOCV_END(databuf)
#else
    char *tmp_buf;
    extern char *crypt(const char *, const char *);
#   define CRYPT_END() rb_nativethread_lock_unlock(&crypt_mutex.lock)
#endif
    VALUE result;
    const char *s, *saltp;
    char *res;
#ifdef BROKEN_CRYPT
    char salt_8bit_clean[3];
#endif

    StringValue(salt);
    mustnot_wchar(str);
    mustnot_wchar(salt);
    s = StringValueCStr(str);
    saltp = RSTRING_PTR(salt);
    if (RSTRING_LEN(salt) < 2 || !saltp[0] || !saltp[1]) {
        rb_raise(rb_eArgError, "salt too short (need >=2 bytes)");
    }

#ifdef BROKEN_CRYPT
    if (!ISASCII((unsigned char)saltp[0]) || !ISASCII((unsigned char)saltp[1])) {
        salt_8bit_clean[0] = saltp[0] & 0x7f;
        salt_8bit_clean[1] = saltp[1] & 0x7f;
        salt_8bit_clean[2] = '\0';
        saltp = salt_8bit_clean;
    }
#endif
#ifdef HAVE_CRYPT_R
    data = ALLOCV(databuf, sizeof(struct crypt_data));
# ifdef HAVE_STRUCT_CRYPT_DATA_INITIALIZED
    data->initialized = 0;
# endif
    res = crypt_r(s, saltp, data);
#else
    rb_nativethread_lock_lock(&crypt_mutex.lock);
    res = crypt(s, saltp);
#endif
    if (!res) {
        int err = errno;
        CRYPT_END();
        rb_syserr_fail(err, "crypt");
    }
#ifdef HAVE_CRYPT_R
    result = rb_str_new_cstr(res);
    CRYPT_END();
#else
    // We need to copy this buffer because it's static and we need to unlock the mutex
    // before allocating a new object (the string to be returned). If we allocate while
    // holding the lock, we could run GC which fires the VM barrier and causes a deadlock
    // if other ractors are waiting on this lock.
    size_t res_size = strlen(res)+1;
    tmp_buf = ALLOCA_N(char, res_size); // should be small enough to alloca
    memcpy(tmp_buf, res, res_size);
    res = tmp_buf;
    CRYPT_END();
    result = rb_str_new_cstr(res);
#endif
    return result;
}

#- ⇒ `String` #dedup ⇒ `String`

Alias for #-@.

#delete(*selectors) ⇒ `String`

Returns a new string that is a copy of self with certain characters removed; the removed characters are all instances of those specified by the given string selectors.

For one 1-character selector, removes all instances of that character:

s = 'abracadabra'
s.delete('a') # => "brcdbr"
s.delete('b') # => "aracadara"
s.delete('x') # => "abracadabra"
s.delete('')  # => "abracadabra"

s = 'тест'
s.delete('т') # => "ес"
s.delete('е') # => "тст"

s = 'よろしくお願いします'
s.delete('よ') # => "ろしくお願いします"
s.delete('し') # => "よろくお願います"

For one multi-character selector, removes all instances of the specified characters:

s = 'abracadabra'
s.delete('ab')     # => "rcdr"
s.delete('abc')    # => "rdr"
s.delete('abcd')   # => "rr"
s.delete('abcdr')  # => ""
s.delete('abcdrx') # => ""

Order and repetition do not matter:

s.delete('ba')   == s.delete('ab') # => true
s.delete('baab') == s.delete('ab') # => true

For multiple selectors, forms a single selector that is the intersection of characters in all selectors and removes all instances of characters specified by that selector:

s = 'abcdefg'
s.delete('abcde', 'dcbfg') == s.delete('bcd') # => true
s.delete('abc', 'def')     == s.delete('')    # => true

In a character selector, three characters get special treatment:

A caret ('^') functions as a negation operator for the immediately following characters:
```
s = 'abracadabra'
s.delete('^bc') # => "bcb"  # Deletes all except 'b' and 'c'.
```

A hyphen ('-') between two other characters defines a range of characters:

s = 'abracadabra'
s.delete('a-c') # => "rdr"  # Deletes all 'a', 'b', and 'c'.

A backslash ('\') acts as an escape for a caret, a hyphen, or another backslash:

s = 'abracadabra'
s.delete('\^bc')           # => "araadara"   # Deletes all '^', 'b', and 'c'.
s.delete('a\-c')           # => "brdbr"      # Deletes all 'a', '-', and 'c'.
'foo\bar\baz'.delete('\\') # => "foobarbaz"  # Deletes all '\'.

These usages may be mixed:

s = 'abracadabra'
s.delete('a-cq-t') # => "d"         # Multiple ranges.
s.delete('ac-d')   # => "brbr"      # Range mixed with plain characters.
s.delete('^a-c')   # => "abacaaba"  # Range mixed with negation.

For multiple selectors, all forms may be used, including negations, ranges, and escapes.

s = 'abracadabra'
s.delete('^abc', '^def') == s.delete('^abcdef') # => true
s.delete('a-e', 'c-g')   == s.delete('cde')     # => true
s.delete('^abc', 'c-g')  == s.delete('defg')    # => true

Related: see Converting to New String.

[ GitHub ]

# File 'string.c', line 8831


static VALUE
rb_str_delete(int argc, VALUE *argv, VALUE str)
{
    str = str_duplicate(rb_cString, str);
    rb_str_delete_bang(argc, argv, str);
    return str;
}

#delete!(*selectors) ⇒ `self`^?

Like #delete, but modifies self in place; returns self if any characters were deleted, nil otherwise.

Related: see Modifying.

[ GitHub ]

# File 'string.c', line 8761


static VALUE
rb_str_delete_bang(int argc, VALUE *argv, VALUE str)
{
    char squeez[TR_TABLE_SIZE];
    rb_encoding *enc = 0;
    char *s, *send, *t;
    VALUE del = 0, nodel = 0;
    int modify = 0;
    int i, ascompat, cr;

    if (RSTRING_LEN(str) == 0 || !RSTRING_PTR(str)) return Qnil;
    rb_check_arity(argc, 1, UNLIMITED_ARGUMENTS);
    for (i=0; i<argc; i++) {
        VALUE s = argv[i];

        StringValue(s);
        enc = rb_enc_check(str, s);
        tr_setup_table(s, squeez, i==0, &del, &nodel, enc);
    }

    str_modify_keep_cr(str);
    ascompat = rb_enc_asciicompat(enc);
    s = t = RSTRING_PTR(str);
    send = RSTRING_END(str);
    cr = ascompat ? ENC_CODERANGE_7BIT : ENC_CODERANGE_VALID;
    while (s < send) {
        unsigned int c;
        int clen;

        if (ascompat && (c = *(unsigned char*)s) < 0x80) {
            if (squeez[c]) {
                modify = 1;
            }
            else {
                if (t != s) *t = c;
                t++;
            }
            s++;
        }
        else {
            c = rb_enc_codepoint_len(s, send, &clen, enc);

            if (tr_find(c, squeez, del, nodel)) {
                modify = 1;
            }
            else {
                if (t != s) rb_enc_mbcput(c, t, enc);
                t += clen;
                if (cr == ENC_CODERANGE_7BIT) cr = ENC_CODERANGE_VALID;
            }
            s += clen;
        }
    }
    TERM_FILL(t, TERM_LEN(str));
    STR_SET_LEN(str, t - RSTRING_PTR(str));
    ENC_CODERANGE_SET(str, cr);

    if (modify) return str;
    return Qnil;
}

#delete_prefix(prefix) ⇒ `String`

Returns a copy of self with leading substring prefix removed:

'oof'.delete_prefix('o')          # => "of"
'oof'.delete_prefix('oo')         # => "f"
'oof'.delete_prefix('oof')        # => ""
'oof'.delete_prefix('x')          # => "oof"
'тест'.delete_prefix('те')        # => "ст"
'こんにちは'.delete_prefix('こん')  # => "にちは"

Related: see Converting to New String.

[ GitHub ]

# File 'string.c', line 11312


static VALUE
rb_str_delete_prefix(VALUE str, VALUE prefix)
{
    long prefixlen;

    prefixlen = deleted_prefix_length(str, prefix);
    if (prefixlen <= 0) return str_duplicate(rb_cString, str);

    return rb_str_subseq(str, prefixlen, RSTRING_LEN(str) - prefixlen);
}

#delete_prefix!(prefix) ⇒ `self`^?

Like #delete_prefix, except that self is modified in place; returns self if the prefix is removed, nil otherwise.

Related: see Modifying.

[ GitHub ]

# File 'string.c', line 11292


static VALUE
rb_str_delete_prefix_bang(VALUE str, VALUE prefix)
{
    long prefixlen;
    str_modify_keep_cr(str);

    prefixlen = deleted_prefix_length(str, prefix);
    if (prefixlen <= 0) return Qnil;

    return rb_str_drop_bytes(str, prefixlen);
}

#delete_suffix(suffix) ⇒ `String`

Returns a copy of self with trailing substring suffix removed:

'foo'.delete_suffix('o')           # => "fo"
'foo'.delete_suffix('oo')          # => "f"
'foo'.delete_suffix('foo')         # => ""
'foo'.delete_suffix('f')           # => "foo"
'foo'.delete_suffix('x')           # => "foo"
'тест'.delete_suffix('ст')         # => "те"
'こんにちは'.delete_suffix('ちは')  # => "こんに"

Related: see Converting to New String.

[ GitHub ]

# File 'string.c', line 11396


static VALUE
rb_str_delete_suffix(VALUE str, VALUE suffix)
{
    long suffixlen;

    suffixlen = deleted_suffix_length(str, suffix);
    if (suffixlen <= 0) return str_duplicate(rb_cString, str);

    return rb_str_subseq(str, 0, RSTRING_LEN(str) - suffixlen);
}

#delete_suffix!(suffix) ⇒ `self`^?

Like #delete_suffix, except that self is modified in place; returns self if the suffix is removed, nil otherwise.

Related: see Modifying.

[ GitHub ]

# File 'string.c', line 11368


static VALUE
rb_str_delete_suffix_bang(VALUE str, VALUE suffix)
{
    long olen, suffixlen, len;
    str_modifiable(str);

    suffixlen = deleted_suffix_length(str, suffix);
    if (suffixlen <= 0) return Qnil;

    olen = RSTRING_LEN(str);
    str_modify_keep_cr(str);
    len = olen - suffixlen;
    STR_SET_LEN(str, len);
    TERM_FILL(&RSTRING_PTR(str)[len], TERM_LEN(str));
    if (ENC_CODERANGE(str) != ENC_CODERANGE_7BIT) {
        ENC_CODERANGE_CLEAR(str);
    }
    return str;
}

#downcase(mapping) ⇒ `String`

Returns a new string containing the downcased characters in self:

'Hello, World!'.downcase      # => "hello, world!"
'ТЕСТ'.downcase               # => "тест"
'よろしくお願いします'.downcase # => "よろしくお願いします"

Some characters do not have upcased and downcased versions.

The casing may be affected by the given mapping; see Case Mapping.

Related: see Converting to New String.

[ GitHub ]

# File 'string.c', line 8107


static VALUE
rb_str_downcase(int argc, VALUE *argv, VALUE str)
{
    rb_encoding *enc;
    OnigCaseFoldType flags = ONIGENC_CASE_DOWNCASE;
    VALUE ret;

    flags = check_case_options(argc, argv, flags);
    enc = str_true_enc(str);
    if (case_option_single_p(flags, enc, str)) {
        ret = rb_str_new(RSTRING_PTR(str), RSTRING_LEN(str));
        str_enc_copy_direct(ret, str);
        downcase_single(ret);
    }
    else if (flags&ONIGENC_CASE_ASCII_ONLY) {
        ret = rb_str_new(0, RSTRING_LEN(str));
        rb_str_ascii_casemap(str, ret, &flags, enc);
    }
    else {
        ret = rb_str_casemap(str, &flags, enc);
    }

    return ret;
}

#downcase!(mapping) ⇒ `self`^?

Like #downcase, except that:

Changes character casings in self (not in a copy of self).
Returns self if any changes are made, nil otherwise.

Related: See Modifying.

[ GitHub ]

# File 'string.c', line 8076


static VALUE
rb_str_downcase_bang(int argc, VALUE *argv, VALUE str)
{
    rb_encoding *enc;
    OnigCaseFoldType flags = ONIGENC_CASE_DOWNCASE;

    flags = check_case_options(argc, argv, flags);
    str_modify_keep_cr(str);
    enc = str_true_enc(str);
    if (case_option_single_p(flags, enc, str)) {
        if (downcase_single(str))
            flags |= ONIGENC_CASE_MODIFIED;
    }
    else if (flags&ONIGENC_CASE_ASCII_ONLY)
        rb_str_ascii_casemap(str, str, &flags, enc);
    else
        str_shared_replace(str, rb_str_casemap(str, &flags, enc));

    if (ONIGENC_CASE_MODIFIED&flags) return str;
    return Qnil;
}

#dump ⇒ `String`

Returns a printable version of self, enclosed in double-quotes:

'hello'.dump     # => "\"hello\""

Certain special characters are rendered with escapes:

'"'.dump  # => "\"\\\"\""
'\\'.dump # => "\"\\\\\""

Non-printing characters are rendered with escapes:

s = ''
s << 7   # Alarm (bell).
s << 8   # Back space.
s << 9   # Horizontal tab.
s << 10  # Line feed.
s << 11  # Vertical tab.
s << 12  # Form feed.
s << 13  # Carriage return.
s        # => "\a\b\t\n\v\f\r"
s.dump   # => "\"\\a\\b\\t\\n\\v\\f\\r\""

If self is encoded in UTF-8 and contains Unicode characters, renders Unicode characters in Unicode escape sequence:

'тест'.dump     # => "\"\\u0442\\u0435\\u0441\\u0442\""
'こんにちは'.dump # => "\"\\u3053\\u3093\\u306B\\u3061\\u306F\""

If the encoding of self is not ASCII-compatible (i.e., self.encoding.ascii_compatible? returns false), renders all ASCII-compatible bytes as ASCII characters and all other bytes as hexadecimal. Appends .dup.force_encoding(\"encoding\"), where <encoding> is self.encoding.name:

s = 'hello'
s.encoding                # => #<Encoding:UTF-8>
s.dump                    # => "\"hello\""
s.encode('utf-16').dump   # => "\"\\xFE\\xFF\\x00h\\x00e\\x00l\\x00l\\x00o\".dup.force_encoding(\"UTF-16\")"
s.encode('utf-16le').dump # => "\"h\\x00e\\x00l\\x00l\\x00o\\x00\".dup.force_encoding(\"UTF-16LE\")"

s = 'тест'
s.encoding                # => #<Encoding:UTF-8>
s.dump                    # => "\"\\u0442\\u0435\\u0441\\u0442\""
s.encode('utf-16').dump   # => "\"\\xFE\\xFF\\x04B\\x045\\x04A\\x04B\".dup.force_encoding(\"UTF-16\")"
s.encode('utf-16le').dump # => "\"B\\x045\\x04A\\x04B\\x04\".dup.force_encoding(\"UTF-16LE\")"

s = 'こんにちは'
s.encoding                # => #<Encoding:UTF-8>
s.dump                    # => "\"\\u3053\\u3093\\u306B\\u3061\\u306F\""
s.encode('utf-16').dump   # => "\"\\xFE\\xFF0S0\\x930k0a0o\".dup.force_encoding(\"UTF-16\")"
s.encode('utf-16le').dump # => "\"S0\\x930k0a0o0\".dup.force_encoding(\"UTF-16LE\")"

Related: see Converting to New String.

[ GitHub ]

# File 'string.c', line 7347


VALUE
rb_str_dump(VALUE str)
{
    int encidx = rb_enc_get_index(str);
    rb_encoding *enc = rb_enc_from_index(encidx);
    long len;
    const char *p, *pend;
    char *q, *qend;
    VALUE result;
    int u8 = (encidx == rb_utf8_encindex());
    static const char nonascii_suffix[] = ".dup.force_encoding(\"%s\")";

    len = 2;			/* "" */
    if (!rb_enc_asciicompat(enc)) {
        len += strlen(nonascii_suffix) - rb_strlen_lit("%s");
        len += strlen(enc->name);
    }

    p = RSTRING_PTR(str); pend = p + RSTRING_LEN(str);
    while (p < pend) {
        int clen;
        unsigned char c = *p++;

        switch (c) {
          case '"':  case '\\':
          case '\n': case '\r':
          case '\t': case '\f':
          case '\013': case '\010': case '\007': case '\033':
            clen = 2;
            break;

          case '#':
            clen = IS_EVSTR(p, pend) ? 2 : 1;
            break;

          default:
            if (ISPRINT(c)) {
                clen = 1;
            }
            else {
                if (u8 && c > 0x7F) {	/* \u notation */
                    int n = rb_enc_precise_mbclen(p-1, pend, enc);
                    if (MBCLEN_CHARFOUND_P(n)) {
                        unsigned int cc = rb_enc_mbc_to_codepoint(p-1, pend, enc);
                        if (cc <= 0xFFFF)
                            clen = 6;  /* \uXXXX */
                        else if (cc <= 0xFFFFF)
                            clen = 9;  /* \u{XXXXX} */
                        else
                            clen = 10; /* \u{XXXXXX} */
                        p += MBCLEN_CHARFOUND_LEN(n)-1;
                        break;
                    }
                }
                clen = 4;	/* \xNN */
            }
            break;
        }

        if (clen > LONG_MAX - len) {
            rb_raise(rb_eRuntimeError, "string size too big");
        }
        len += clen;
    }

    result = rb_str_new(0, len);
    p = RSTRING_PTR(str); pend = p + RSTRING_LEN(str);
    q = RSTRING_PTR(result); qend = q + len + 1;

    *q++ = '"';
    while (p < pend) {
        unsigned char c = *p++;

        if (c == '"' || c == '\\') {
            *q++ = '\\';
            *q++ = c;
        }
        else if (c == '#') {
            if (IS_EVSTR(p, pend)) *q++ = '\\';
            *q++ = '#';
        }
        else if (c == '\n') {
            *q++ = '\\';
            *q++ = 'n';
        }
        else if (c == '\r') {
            *q++ = '\\';
            *q++ = 'r';
        }
        else if (c == '\t') {
            *q++ = '\\';
            *q++ = 't';
        }
        else if (c == '\f') {
            *q++ = '\\';
            *q++ = 'f';
        }
        else if (c == '\013') {
            *q++ = '\\';
            *q++ = 'v';
        }
        else if (c == '\010') {
            *q++ = '\\';
            *q++ = 'b';
        }
        else if (c == '\007') {
            *q++ = '\\';
            *q++ = 'a';
        }
        else if (c == '\033') {
            *q++ = '\\';
            *q++ = 'e';
        }
        else if (ISPRINT(c)) {
            *q++ = c;
        }
        else {
            *q++ = '\\';
            if (u8) {
                int n = rb_enc_precise_mbclen(p-1, pend, enc) - 1;
                if (MBCLEN_CHARFOUND_P(n)) {
                    int cc = rb_enc_mbc_to_codepoint(p-1, pend, enc);
                    p += n;
                    if (cc <= 0xFFFF)
                        snprintf(q, qend-q, "u%04X", cc);    /* \uXXXX */
                    else
                        snprintf(q, qend-q, "u{%X}", cc);  /* \u{XXXXX} or \u{XXXXXX} */
                    q += strlen(q);
                    continue;
                }
            }
            snprintf(q, qend-q, "x%02X", c);
            q += 3;
        }
    }
    *q++ = '"';
    *q = '\0';
    if (!rb_enc_asciicompat(enc)) {
        snprintf(q, qend-q, nonascii_suffix, enc->name);
        encidx = rb_ascii8bit_encindex();
    }
    /* result from dump is ASCII */
    rb_enc_associate_index(result, encidx);
    ENC_CODERANGE_SET(result, ENC_CODERANGE_7BIT);
    return result;
}

#dup

This method is for internal use only.

[ GitHub ]

# File 'string.c', line 2000


VALUE
rb_str_dup_m(VALUE str)
{
    if (LIKELY(BARE_STRING_P(str))) {
        return str_duplicate(rb_cString, str);
    }
    else {
        return rb_obj_dup(str);
    }
}

#each_byte {|byte| ... } ⇒ `self` #each_byte ⇒ Enumerator

With a block given, calls the block with each successive byte from self; returns self:

a = []
'hello'.each_byte {|byte| a.push(byte) }     # Five 1-byte characters.
a # => [104, 101, 108, 108, 111]
a = []
'тест'.each_byte {|byte| a.push(byte) }      # Four 2-byte characters.
a # => [209, 130, 208, 181, 209, 129, 209, 130]
a = []
'こんにちは'.each_byte {|byte| a.push(byte) }  # Five 3-byte characters.
a # => [227, 129, 147, 227, 130, 147, 227, 129, 171, 227, 129, 161, 227, 129, 175]

With no block given, returns an enumerator.

Related: see Iterating.

[ GitHub ]

# File 'string.c', line 9683


static VALUE
rb_str_each_byte(VALUE str)
{
    RETURN_SIZED_ENUMERATOR(str, 0, 0, rb_str_each_byte_size);
    return rb_str_enumerate_bytes(str, 0);
}

#each_char {|char| ... } ⇒ `self` #each_char ⇒ Enumerator

With a block given, calls the block with each successive character from self; returns self:

a = []
'hello'.each_char do |char|
  a.push(char)
end
a # => ["h", "e", "l", "l", "o"]
a = []
'тест'.each_char do |char|
  a.push(char)
end
a # => ["т", "е", "с", "т"]
a = []
'こんにちは'.each_char do |char|
  a.push(char)
end
a # => ["こ", "ん", "に", "ち", "は"]

With no block given, returns an enumerator.

Related: see Iterating.

[ GitHub ]

# File 'string.c', line 9752


static VALUE
rb_str_each_char(VALUE str)
{
    RETURN_SIZED_ENUMERATOR(str, 0, 0, rb_str_each_char_size);
    return rb_str_enumerate_chars(str, 0);
}

#each_codepoint {|codepoint| ... } ⇒ `self` #each_codepoint ⇒ Enumerator

With a block given, calls the block with each successive codepoint from self; each codepoint is the integer value for a character; returns self:

a = []
'hello'.each_codepoint do |codepoint|
  a.push(codepoint)
end
a # => [104, 101, 108, 108, 111]
a = []
'тест'.each_codepoint do |codepoint|
  a.push(codepoint)
end
a # => [1090, 1077, 1089, 1090]
a = []
'こんにちは'.each_codepoint do |codepoint|
  a.push(codepoint)
end
a # => [12371, 12435, 12395, 12385, 12399]

With no block given, returns an enumerator.

Related: see Iterating.

[ GitHub ]

# File 'string.c', line 9812


static VALUE
rb_str_each_codepoint(VALUE str)
{
    RETURN_SIZED_ENUMERATOR(str, 0, 0, rb_str_each_char_size);
    return rb_str_enumerate_codepoints(str, 0);
}

#each_grapheme_cluster {|grapheme_cluster| ... } ⇒ `self` #each_grapheme_cluster ⇒ Enumerator

With a block given, calls the given block with each successive grapheme cluster from self (see Unicode Grapheme Cluster Boundaries); returns self:

a = []
'hello'.each_grapheme_cluster do |grapheme_cluster|
  a.push(grapheme_cluster)
end
a  # => ["h", "e", "l", "l", "o"]

a = []
'тест'.each_grapheme_cluster do |grapheme_cluster|
  a.push(grapheme_cluster)
end
a # => ["т", "е", "с", "т"]

a = []
'こんにちは'.each_grapheme_cluster do |grapheme_cluster|
  a.push(grapheme_cluster)
end
a # => ["こ", "ん", "に", "ち", "は"]

With no block given, returns an enumerator.

Related: see Iterating.

[ GitHub ]

# File 'string.c', line 9982


static VALUE
rb_str_each_grapheme_cluster(VALUE str)
{
    RETURN_SIZED_ENUMERATOR(str, 0, 0, rb_str_each_grapheme_cluster_size);
    return rb_str_enumerate_grapheme_clusters(str, 0);
}

#each_line(record_separator = $/, chomp: false) {|substring| ... } ⇒ `self` #each_line(record_separator = $/, chomp: false) ⇒ Enumerator

With a block given, forms the substrings (lines) that are the result of splitting self at each occurrence of the given record_separator; passes each line to the block; returns self.

With the default record_separator:

$/ # => "\n"
s = <<~EOT
This is the first line.
This is line two.

This is line four.
This is line five.
EOT
s.each_line {|line| p line }

Output:

"This is the first line.\n"
"This is line two.\n"
"\n"
"This is line four.\n"
"This is line five.\n"

With a different record_separator:

record_separator = ' is '
s.each_line(record_separator) {|line| p line }

Output:

"This is "
"the first line.\nThis is "
"line two.\n\nThis is "
"line four.\nThis is "
"line five.\n"

With #chomp as true, removes the trailing record_separator from each line:

s.each_line(chomp: true) {|line| p line }

Output:

"This is the first line."
"This is line two."
""
"This is line four."
"This is line five."

With an empty string as record_separator, forms and passes “paragraphs” by splitting at each occurrence of two or more newlines:

record_separator = ''
s.each_line(record_separator) {|line| p line }

Output:

"This is the first line.\nThis is line two.\n\n"
"This is line four.\nThis is line five.\n"

With no block given, returns an enumerator.

Related: see Iterating.

[ GitHub ]

# File 'string.c', line 9589


static VALUE
rb_str_each_line(int argc, VALUE *argv, VALUE str)
{
    RETURN_SIZED_ENUMERATOR(str, argc, argv, 0);
    return rb_str_enumerate_lines(argc, argv, str, 0);
}

#encode(dst_encoding = Encoding.default_internal, enc_opts) ⇒ `String` #encode(dst_encoding, src_encoding, enc_opts) ⇒ `String`

Returns a copy of self transcoded as determined by dst_encoding; see Encodings.

By default, raises an exception if self contains an invalid byte or a character not defined in dst_encoding; that behavior may be modified by encoding options; see below.

With no arguments:

Uses the same encoding if Encoding.default_internal is nil (the default):

Encoding.default_internal # => nil
s = "Ruby\x99".force_encoding('Windows-1252')
s.encoding                # => #<Encoding:Windows-1252>
s.bytes                   # => [82, 117, 98, 121, 153]
t = s.encode              # => "Ruby\x99"
t.encoding                # => #<Encoding:Windows-1252>
t.bytes                   # => [82, 117, 98, 121, 226, 132, 162]

Otherwise, uses the encoding Encoding.default_internal:

Encoding.default_internal = 'UTF-8'
t = s.encode              # => "Ruby™"
t.encoding                # => #<Encoding:UTF-8>

With only argument dst_encoding given, uses that encoding:

s = "Ruby\x99".force_encoding('Windows-1252')
s.encoding            # => #<Encoding:Windows-1252>
t = s.encode('UTF-8') # => "Ruby™"
t.encoding            # => #<Encoding:UTF-8>

With arguments dst_encoding and src_encoding given, interprets self using src_encoding, encodes the new string using dst_encoding:

s = "Ruby\x99"
t = s.encode('UTF-8', 'Windows-1252') # => "Ruby™"
t.encoding                            # => #<Encoding:UTF-8>

Optional keyword arguments enc_opts specify encoding options; see {Encoding Options}.

Please note that, unless invalid: :replace option is given, conversion from an encoding enc to the same encoding enc (independent of whether enc is given explicitly or implicitly) is a no-op, i.e. the string is simply copied without any changes, and no exceptions are raised, even if there are invalid bytes.

Related: see Converting to New String.

[ GitHub ]

# File 'transcode.c', line 2965


static VALUE
str_encode(int argc, VALUE *argv, VALUE str)
{
    VALUE newstr = str;
    int encidx = str_transcode(argc, argv, &newstr);
    return encoded_dup(newstr, str, encidx);
}

#encode!(dst_encoding = Encoding.default_internal, enc_opts) ⇒ `self` #encode!(dst_encoding, src_encoding, enc_opts) ⇒ `self`

Like #encode, but applies encoding changes to self; returns self.

Related: see Modifying.

[ GitHub ]

# File 'transcode.c', line 2934


static VALUE
str_encode_bang(int argc, VALUE *argv, VALUE str)
{
    VALUE newstr;
    int encidx;

    rb_check_frozen(str);

    newstr = str;
    encidx = str_transcode(argc, argv, &newstr);

    if (encidx < 0) return str;
    if (newstr == str) {
        rb_enc_associate_index(str, encidx);
        return str;
    }
    rb_str_shared_replace(str, newstr);
    return str_encode_associate(str, encidx);
}

#encoding ⇒ Encoding

Alias for Regexp#encoding.

#end_with?(*strings) ⇒ `Boolean`

Returns whether self ends with any of the given strings:

'foo'.end_with?('oo')         # => true
'foo'.end_with?('bar', 'oo')  # => true
'foo'.end_with?('bar', 'baz') # => false
'foo'.end_with?('')           # => true
'тест'.end_with?('т')         # => true
'こんにちは'.end_with?('は')   # => true

Related: see Querying.

[ GitHub ]

# File 'string.c', line 11207


static VALUE
rb_str_end_with(int argc, VALUE *argv, VALUE str)
{
    int i;

    for (i=0; i<argc; i++) {
        VALUE tmp = argv[i];
        const char *p, *s, *e;
        long slen, tlen;
        rb_encoding *enc;

        StringValue(tmp);
        enc = rb_enc_check(str, tmp);
        if ((tlen = RSTRING_LEN(tmp)) == 0) return Qtrue;
        if ((slen = RSTRING_LEN(str)) < tlen) continue;
        p = RSTRING_PTR(str);
        e = p + slen;
        s = e - tlen;
        if (!at_char_boundary(p, s, e, enc))
            continue;
        if (memcmp(s, RSTRING_PTR(tmp), tlen) == 0)
            return Qtrue;
    }
    return Qfalse;
}

#eql?(object) ⇒ `Boolean`

Returns whether self and object have the same length and content:

s = 'foo'
s.eql?('foo')  # => true
s.eql?('food') # => false
s.eql?('FOO')  # => false

Returns false if the two strings’ encodings are not compatible:

s0 = "äöü"                           # => "äöü"
s1 = s0.encode(Encoding::ISO_8859_1) # => "\xE4\xF6\xFC"
s0.encoding                          # => #<Encoding:UTF-8>
s1.encoding                          # => #<Encoding:ISO-8859-1>
s0.eql?(s1)                          # => false

See Encodings.

Related: see Querying.

[ GitHub ]

# File 'string.c', line 4285


VALUE
rb_str_eql(VALUE str1, VALUE str2)
{
    if (str1 == str2) return Qtrue;
    if (!RB_TYPE_P(str2, T_STRING)) return Qfalse;
    return rb_str_eql_internal(str1, str2);
}

#force_encoding(encoding) ⇒ `self`

Changes the encoding of self to the given #encoding, which may be a string encoding name or an ::Encoding object; does not change the underlying bytes; returns self:

s = 'łał'
s.bytes                   # => [197, 130, 97, 197, 130]
s.encoding                # => #<Encoding:UTF-8>
s.force_encoding('ascii') # => "\xC5\x82a\xC5\x82"
s.encoding                # => #<Encoding:US-ASCII>
s.valid_encoding?         # => true
s.bytes                   # => [197, 130, 97, 197, 130]

Makes the change even if the given #encoding is invalid for self (as is the change above):

s.valid_encoding?         # => false

See Encodings.

Related: see Modifying.

[ GitHub ]

# File 'string.c', line 11440


static VALUE
rb_str_force_encoding(VALUE str, VALUE enc)
{
    str_modifiable(str);

    rb_encoding *encoding = rb_to_encoding(enc);
    int idx = rb_enc_to_index(encoding);

    // If the encoding is unchanged, we do nothing.
    if (ENCODING_GET(str) == idx) {
        return str;
    }

    rb_enc_associate_index(str, idx);

    // If the coderange was 7bit and the new encoding is ASCII-compatible
    // we can keep the coderange.
    if (ENC_CODERANGE(str) == ENC_CODERANGE_7BIT && encoding && rb_enc_asciicompat(encoding)) {
        return str;
    }

    ENC_CODERANGE_CLEAR(str);
    return str;
}

#freeze

This method is for internal use only.

[ GitHub ]

# File 'string.c', line 3275


VALUE
rb_str_freeze(VALUE str)
{
    if (CHILLED_STRING_P(str)) {
        FL_UNSET_RAW(str, STR_CHILLED);
    }

    if (OBJ_FROZEN(str)) return str;
    rb_str_resize(str, RSTRING_LEN(str));
    return rb_obj_freeze(str);
}

#getbyte(index) ⇒ Integer^?

Returns the byte at zero-based #index as an integer:

s = 'foo'
s.getbyte(0)    # => 102
s.getbyte(1)    # => 111
s.getbyte(2)    # => 111

Counts backward from the end if #index is negative:

s.getbyte(-3) # => 102

Returns nil if #index is out of range:

s.getbyte(3)  # => nil
s.getbyte(-4) # => nil

More examples:

s = 'тест'
s.bytes      # => [209, 130, 208, 181, 209, 129, 209, 130]
s.getbyte(2) # => 208
s = 'こんにちは'
s.bytes      # => [227, 129, 147, 227, 130, 147, 227, 129, 171, 227, 129, 161, 227, 129, 175]
s.getbyte(2) # => 147

Related: see Converting to Non-String.

[ GitHub ]

# File 'string.c', line 6622


VALUE
rb_str_getbyte(VALUE str, VALUE index)
{
    long pos = NUM2LONG(index);

    if (pos < 0)
        pos += RSTRING_LEN(str);
    if (pos < 0 ||  RSTRING_LEN(str) <= pos)
        return Qnil;

    return INT2FIX((unsigned char)RSTRING_PTR(str)[pos]);
}

#grapheme_clusters ⇒ `array_of_grapheme_clusters`

Returns an array of the grapheme clusters in self (see Unicode Grapheme Cluster Boundaries):

s = "ä-pqr-b̈-xyz-c̈"
s.size                   # => 16
s.bytesize               # => 19
s.grapheme_clusters.size # => 13
s.grapheme_clusters
# => ["ä", "-", "p", "q", "r", "-", "b̈", "-", "x", "y", "z", "-", "c̈"]

Details:

s = "ä"
s.grapheme_clusters             # => ["ä"]           # One grapheme cluster.
s.bytes                         # => [97, 204, 136]  # Three bytes.
s.chars                         # => ["a", "̈"]       # Two characters.
s.chars.map {|char| char.ord }  # => [97, 776]       # Their values.

Related: see Converting to Non-String.

[ GitHub ]

# File 'string.c', line 9997


static VALUE
rb_str_grapheme_clusters(VALUE str)
{
    VALUE ary = WANTARRAY("grapheme_clusters", rb_str_strlen(str));
    return rb_str_enumerate_grapheme_clusters(str, ary);
}

#gsub(pattern, replacement) ⇒ `String` #gsub(pattern) {|match| ... } ⇒ `String` #gsub(pattern) ⇒ Enumerator

Returns a copy of self with zero or more substrings replaced.

Argument pattern may be a string or a Regexp; argument replacement may be a string or a ::Hash. Varying types for the argument values makes this method very versatile.

Below are some simple examples; for many more examples, see Substitution Methods.

With arguments pattern and string replacement given, replaces each matching substring with the given replacement string:

s = 'abracadabra'
s.gsub('ab', 'AB')   # => "ABracadABra"
s.gsub(/[a-c]/, 'X') # => "XXrXXXdXXrX"

With arguments pattern and hash replacement given, replaces each matching substring with a value from the given replacement hash, or removes it:

h = {'a' => 'A', 'b' => 'B', 'c' => 'C'}
s.gsub(/[a-c]/, h) # => "ABrACAdABrA"  # 'a', 'b', 'c' replaced.
s.gsub(/[a-d]/, h) # => "ABrACAABrA"   # 'd' removed.

With argument pattern and a block given, calls the block with each matching substring; replaces that substring with the block’s return value:

s.gsub(/[a-d]/) {|substring| substring.upcase }
# => "ABrACADABrA"

With argument pattern and no block given, returns a new ::Enumerator.

Related: see Converting to New String.

[ GitHub ]

# File 'string.c', line 6543


static VALUE
rb_str_gsub(int argc, VALUE *argv, VALUE str)
{
    return str_gsub(argc, argv, str, 0);
}

#gsub!(pattern, replacement) ⇒ `self`^? #gsub!(pattern) {|match| ... } ⇒ `self`^? #gsub!(pattern) ⇒ Enumerator

Like #gsub, except that:

Performs substitutions in self (not in a copy of self).
Returns self if any characters are removed, nil otherwise.

Related: see Modifying.

[ GitHub ]

# File 'string.c', line 6492


static VALUE
rb_str_gsub_bang(int argc, VALUE *argv, VALUE str)
{
    str_modify_keep_cr(str);
    return str_gsub(argc, argv, str, 1);
}

#hash ⇒ Integer

Returns the integer hash value for self.

Two String objects that have identical content and compatible encodings also have the same hash value; see Object#hash and Encodings:

s = 'foo'
h = s.hash       # => -569050784
h == 'foo'.hash  # => true
h == 'food'.hash # => false
h == 'FOO'.hash  # => false

s0 = "äöü"
s1 = s0.encode(Encoding::ISO_8859_1)
s0.encoding        # => #<Encoding:UTF-8>
s1.encoding        # => #<Encoding:ISO-8859-1>
s0.hash == s1.hash # => false

Related: see Querying.

[ GitHub ]

# File 'string.c', line 4177


static VALUE
rb_str_hash_m(VALUE str)
{
    st_index_t hval = rb_str_hash(str);
    return ST2FIX(hval);
}

#hex ⇒ Integer

Interprets the leading substring of self as hexadecimal, possibly signed; returns its value as an integer.

The leading substring is interpreted as hexadecimal when it begins with:

One or more character representing hexadecimal digits (each in one of the ranges '0'..'9', 'a'..'f', or 'A'..'F'); the string to be interpreted ends at the first character that does not represent a hexadecimal digit:

'f'.hex        # => 15
'11'.hex       # => 17
'FFF'.hex      # => 4095
'fffg'.hex     # => 4095
'foo'.hex      # => 15   # 'f' hexadecimal, 'oo' not.
'bar'.hex      # => 186  # 'ba' hexadecimal, 'r' not.
'deadbeef'.hex # => 3735928559

'0x' or '0X', followed by one or more hexadecimal digits:

'0xfff'.hex    # => 4095
'0xfffg'.hex   # => 4095

Any of the above may prefixed with '-', which negates the interpreted value:

'-fff'.hex      # => -4095
'-0xFFF'.hex    # => -4095

For any substring not described above, returns zero:

'xxx'.hex     # => 0
''.hex        # => 0

Note that, unlike #oct, this method interprets only hexadecimal, and not binary, octal, or decimal notations:

'0b111'.hex   # => 45329
'0o777'.hex   # => 0
'0d999'.hex   # => 55705

Related: See Converting to Non-String.

[ GitHub ]

# File 'string.c', line 10638


static VALUE
rb_str_hex(VALUE str)
{
    return rb_str_to_inum(str, 16, FALSE);
}

#include?(other_string) ⇒ `Boolean`

Returns whether self contains other_string:

s = 'bar'
s.include?('ba')  # => true
s.include?('ar')  # => true
s.include?('bar') # => true
s.include?('a')   # => true
s.include?('')    # => true
s.include?('foo') # => false

Related: see Querying.

[ GitHub ]

# File 'string.c', line 7013


VALUE
rb_str_include(VALUE str, VALUE arg)
{
    long i;

    StringValue(arg);
    i = rb_str_index(str, arg, 0);

    return RBOOL(i != -1);
}

#index(pattern, offset = 0) ⇒ Integer^?

Returns the integer position of the first substring that matches the given argument pattern, or nil if none found.

When pattern is a string, returns the index of the first matching substring in self:

'foo'.index('f')         # => 0
'foo'.index('o')         # => 1
'foo'.index('oo')        # => 1
'foo'.index('ooo')       # => nil
'тест'.index('с')        # => 2  # Characters, not bytes.
'こんにちは'.index('ち')  # => 3

When pattern is a ::Regexp, returns the index of the first match in self:

'foo'.index(/o./) # => 1
'foo'.index(/.o/) # => 0

When offset is non-negative, begins the search at position offset; the returned index is relative to the beginning of self:

'bar'.index('r', 0)        # => 2
'bar'.index('r', 1)        # => 2
'bar'.index('r', 2)        # => 2
'bar'.index('r', 3)        # => nil
'bar'.index(/[r-z]/, 0)    # => 2
'тест'.index('с', 1)       # => 2
'тест'.index('с', 2)       # => 2
'тест'.index('с', 3)       # => nil  # Offset in characters, not bytes.
'こんにちは'.index('ち', 2) # => 3

With negative integer argument offset, selects the search position by counting backward from the end of self:

'foo'.index('o', -1)  # => 2
'foo'.index('o', -2)  # => 1
'foo'.index('o', -3)  # => 1
'foo'.index('o', -4)  # => nil
'foo'.index(/o./, -2) # => 1
'foo'.index(/.o/, -2) # => 1

Related: see Querying.

[ GitHub ]

# File 'string.c', line 4545


static VALUE
rb_str_index_m(int argc, VALUE *argv, VALUE str)
{
    VALUE sub;
    VALUE initpos;
    rb_encoding *enc = STR_ENC_GET(str);
    long pos;

    if (rb_scan_args(argc, argv, "11", &sub, &initpos) == 2) {
        long slen = str_strlen(str, enc); /* str's enc */
        pos = NUM2LONG(initpos);
        if (pos < 0 ? (pos += slen) < 0 : pos > slen) {
            if (RB_TYPE_P(sub, T_REGEXP)) {
                rb_backref_set(Qnil);
            }
            return Qnil;
        }
    }
    else {
        pos = 0;
    }

    if (RB_TYPE_P(sub, T_REGEXP)) {
        pos = str_offset(RSTRING_PTR(str), RSTRING_END(str), pos,
                         enc, single_byte_optimizable(str));

        if (rb_reg_search(sub, str, pos, 0) >= 0) {
            VALUE match = rb_backref_get();
            struct re_registers *regs = RMATCH_REGS(match);
            pos = rb_str_sublen(str, BEG(0));
            return LONG2NUM(pos);
        }
    }
    else {
        StringValue(sub);
        pos = rb_str_index(str, sub, pos);
        if (pos >= 0) {
            pos = rb_str_sublen(str, pos);
            return LONG2NUM(pos);
        }
    }
    return Qnil;
}

#replace(other_string) ⇒ `self` #initialize_copy(other_string) ⇒ `self`

Alias for #replace.

#insert(offset, other_string) ⇒ `self`

Inserts the given other_string into self; returns self.

If the given #index is non-negative, inserts other_string at offset #index:

'foo'.insert(0, 'bar')       # => "barfoo"
'foo'.insert(1, 'bar')       # => "fbaroo"
'foo'.insert(3, 'bar')       # => "foobar"
'тест'.insert(2, 'bar')      # => "теbarст"  # Characters, not bytes.
'こんにちは'.insert(2, 'bar') # => "こんbarにちは"

If the #index is negative, counts backward from the end of self and inserts other_string after the offset:

'foo'.insert(-2, 'bar') # => "fobaro"

Related: see Modifying.

[ GitHub ]

# File 'string.c', line 5988


static VALUE
rb_str_insert(VALUE str, VALUE idx, VALUE str2)
{
    long pos = NUM2LONG(idx);

    if (pos == -1) {
        return rb_str_append(str, str2);
    }
    else if (pos < 0) {
        pos++;
    }
    rb_str_update(str, pos, 0, str2);
    return str;
}

#inspect ⇒ `String`

Returns a printable version of self, enclosed in double-quotes.

Most printable characters are rendered simply as themselves:

'abc'.inspect        # => "\"abc\""
'012'.inspect        # => "\"012\""
''.inspect           # => "\"\""
"\u000012".inspect   # => "\"\\u000012\""
'тест'.inspect       # => "\"тест\""
'こんにちは'.inspect  # => "\"こんにちは\""

But printable characters double-quote ('"') and backslash and ('\') are escaped:

'"'.inspect  # => "\"\\\"\""
'\\'.inspect # => "\"\\\\\""

Unprintable characters are the ASCII characters whose values are in range 0..31, along with the character whose value is 127.

Most of these characters are rendered thus:

0.chr.inspect # => "\"\\x00\""
1.chr.inspect # => "\"\\x01\""
2.chr.inspect # => "\"\\x02\""
# ...

A few, however, have special renderings:

7.chr.inspect  # => "\"\\a\""  # BEL
8.chr.inspect  # => "\"\\b\""  # BS
9.chr.inspect  # => "\"\\t\""  # TAB
10.chr.inspect # => "\"\\n\""  # LF
11.chr.inspect # => "\"\\v\""  # VT
12.chr.inspect # => "\"\\f\""  # FF
13.chr.inspect # => "\"\\r\""  # CR
27.chr.inspect # => "\"\\e\""  # ESC

Related: see Converting to Non-String.

[ GitHub ]

# File 'string.c', line 7240


VALUE
rb_str_inspect(VALUE str)
{
    int encidx = ENCODING_GET(str);
    rb_encoding *enc = rb_enc_from_index(encidx);
    const char *p, *pend, *prev;
    char buf[CHAR_ESC_LEN + 1];
    VALUE result = rb_str_buf_new(0);
    rb_encoding *resenc = rb_default_internal_encoding();
    int unicode_p = rb_enc_unicode_p(enc);
    int asciicompat = rb_enc_asciicompat(enc);

    if (resenc == NULL) resenc = rb_default_external_encoding();
    if (!rb_enc_asciicompat(resenc)) resenc = rb_usascii_encoding();
    rb_enc_associate(result, resenc);
    str_buf_cat2(result, "\"");

    p = RSTRING_PTR(str); pend = RSTRING_END(str);
    prev = p;
    while (p < pend) {
        unsigned int c, cc;
        int n;

        n = rb_enc_precise_mbclen(p, pend, enc);
        if (!MBCLEN_CHARFOUND_P(n)) {
            if (p > prev) str_buf_cat(result, prev, p - prev);
            n = rb_enc_mbminlen(enc);
            if (pend < p + n)
                n = (int)(pend - p);
            while (n--) {
                snprintf(buf, CHAR_ESC_LEN, "\\x%02X", *p & 0377);
                str_buf_cat(result, buf, strlen(buf));
                prev = ++p;
            }
            continue;
        }
        n = MBCLEN_CHARFOUND_LEN(n);
        c = rb_enc_mbc_to_codepoint(p, pend, enc);
        p += n;
        if ((asciicompat || unicode_p) &&
          (c == '"'|| c == '\\' ||
            (c == '#' &&
             p < pend &&
             MBCLEN_CHARFOUND_P(rb_enc_precise_mbclen(p,pend,enc)) &&
             (cc = rb_enc_codepoint(p,pend,enc),
              (cc == '$' || cc == '@' || cc == '{'))))) {
            if (p - n > prev) str_buf_cat(result, prev, p - n - prev);
            str_buf_cat2(result, "\\");
            if (asciicompat || enc == resenc) {
                prev = p - n;
                continue;
            }
        }
        switch (c) {
          case '\n': cc = 'n'; break;
          case '\r': cc = 'r'; break;
          case '\t': cc = 't'; break;
          case '\f': cc = 'f'; break;
          case '\013': cc = 'v'; break;
          case '\010': cc = 'b'; break;
          case '\007': cc = 'a'; break;
          case 033: cc = 'e'; break;
          default: cc = 0; break;
        }
        if (cc) {
            if (p - n > prev) str_buf_cat(result, prev, p - n - prev);
            buf[0] = '\\';
            buf[1] = (char)cc;
            str_buf_cat(result, buf, 2);
            prev = p;
            continue;
        }
        /* The special casing of 0x85 (NEXT_LINE) here is because
         * Oniguruma historically treats it as printable, but it
         * doesn't match the print POSIX bracket class or character
         * property in regexps.
         *
         * See Ruby Bug #16842 for details:
         * https://bugs.ruby-lang.org/issues/16842
         */
        if ((enc == resenc && rb_enc_isprint(c, enc) && c != 0x85) ||
            (asciicompat && rb_enc_isascii(c, enc) && ISPRINT(c))) {
            continue;
        }
        else {
            if (p - n > prev) str_buf_cat(result, prev, p - n - prev);
            rb_str_buf_cat_escaped_char(result, c, unicode_p);
            prev = p;
            continue;
        }
    }
    if (p > prev) str_buf_cat(result, prev, p - prev);
    str_buf_cat2(result, "\"");

    return result;
}

#intern ⇒ Symbol Also known as: #to_sym

Returns the ::Symbol object derived from self, creating it if it did not already exist:

'foo'.intern       # => :foo
'тест'.intern      # => :тест
'こんにちは'.intern # => :こんにちは

Related: see Converting to Non-String.

[ GitHub ]

# File 'symbol.c', line 936


VALUE
rb_str_intern(VALUE str)
{
    return sym_find_or_insert_dynamic_symbol(&ruby_global_symbols, str);
}

#length ⇒ Integer Also known as: #size

Returns the count of characters (not bytes) in self:

'foo'.length        # => 3
'тест'.length       # => 4
'こんにちは'.length  # => 5

Contrast with #bytesize:

'foo'.bytesize        # => 3
'тест'.bytesize       # => 8
'こんにちは'.bytesize  # => 15

Related: see Querying.

[ GitHub ]

# File 'string.c', line 2434


VALUE
rb_str_length(VALUE str)
{
    return LONG2NUM(str_strlen(str, NULL));
}

#lines(record_separator = $/, chomp: false) ⇒ `String`

Returns substrings (“lines”) of self according to the given arguments:

s = <<~EOT
This is the first line.
This is line two.

This is line four.
This is line five.
EOT

With the default argument values:

$/ # => "\n"
s.lines
# =>
["This is the first line.\n",
 "This is line two.\n",
 "\n",
 "This is line four.\n",
 "This is line five.\n"]

With a different record_separator:

record_separator = ' is '
s.lines(record_separator)
# =>
["This is ",
 "the first line.\nThis is ",
 "line two.\n\nThis is ",
 "line four.\nThis is ",
 "line five.\n"]

With keyword argument #chomp as true, removes the trailing newline from each line:

s.lines(chomp: true)
# =>
["This is the first line.",
 "This is line two.",
 "",
 "This is line four.",
 "This is line five."]

Related: see Converting to Non-String.

[ GitHub ]

# File 'string.c', line 9647


static VALUE
rb_str_lines(int argc, VALUE *argv, VALUE str)
{
    VALUE ary = WANTARRAY("lines", 0);
    return rb_str_enumerate_lines(argc, argv, str, ary);
}

#ljust(width, pad_string = ' ') ⇒ `String`

Returns a copy of self, left-justified and, if necessary, right-padded with the pad_string:

'hello'.ljust(10)       # => "hello     "
'  hello'.ljust(10)     # => "  hello   "
'hello'.ljust(10, 'ab') # => "helloababa"
'тест'.ljust(10)        # => "тест      "
'こんにちは'.ljust(10)   # => "こんにちは     "

If width <= self.length, returns a copy of self:

'hello'.ljust(5)  # => "hello"
'hello'.ljust(1)  # => "hello"  # Does not truncate to width.

Related: see Converting to New String.

[ GitHub ]

# File 'string.c', line 11047


static VALUE
rb_str_ljust(int argc, VALUE *argv, VALUE str)
{
    return rb_str_justify(argc, argv, str, 'l');
}

#lstrip ⇒ `String`

Returns a copy of self with leading whitespace removed; see Whitespace in Strings:

whitespace = "\x00\t\n\v\f\r "
s = whitespace + 'abc' + whitespace
# => "\u0000\t\n\v\f\r abc\u0000\t\n\v\f\r "
s.lstrip
# => "abc\u0000\t\n\v\f\r "

Related: see Converting to New String.

[ GitHub ]

# File 'string.c', line 10318


static VALUE
rb_str_lstrip(VALUE str)
{
    char *start;
    long len, loffset;
    RSTRING_GETMEM(str, start, len);
    loffset = lstrip_offset(str, start, start+len, STR_ENC_GET(str));
    if (loffset <= 0) return str_duplicate(rb_cString, str);
    return rb_str_subseq(str, loffset, len - loffset);
}

#lstrip! ⇒ `self`^?

Like #lstrip, except that:

Performs stripping in self (not in a copy of self).
Returns self if any characters are stripped, nil otherwise.

Related: see Modifying.

[ GitHub ]

# File 'string.c', line 10279


static VALUE
rb_str_lstrip_bang(VALUE str)
{
    rb_encoding *enc;
    char *start, *s;
    long olen, loffset;

    str_modify_keep_cr(str);
    enc = STR_ENC_GET(str);
    RSTRING_GETMEM(str, start, olen);
    loffset = lstrip_offset(str, start, start+olen, enc);
    if (loffset > 0) {
        long len = olen-loffset;
        s = start + loffset;
        memmove(start, s, len);
        STR_SET_LEN(str, len);
        TERM_FILL(start+len, rb_enc_mbminlen(enc));
        return str;
    }
    return Qnil;
}

#match(pattern, offset = 0) ⇒ MatchData^? #match(pattern, offset = 0) {|matchdata| ... } ⇒ Object

Creates a ::MatchData object based on self and the given arguments; updates {Regexp Global Variables}.

Computes regexp by converting pattern (if not already a ::Regexp).
```
regexp = Regexp.new(pattern)
```
Computes matchdata, which will be either a ::MatchData object or nil (see Regexp#match):
```
matchdata = regexp.match(self[offset..])
```

With no block given, returns the computed matchdata or nil:

'foo'.match('f')    # => #<MatchData "f">
'foo'.match('o')    # => #<MatchData "o">
'foo'.match('x')    # => nil
'foo'.match('f', 1) # => nil
'foo'.match('o', 1) # => #<MatchData "o">

With a block given and computed matchdata non-nil, calls the block with matchdata; returns the block’s return value:

'foo'.match(/o/) {|matchdata| matchdata } # => #<MatchData "o">

With a block given and nil matchdata, does not call the block:

'foo'.match(/x/) {|matchdata| fail 'Cannot happen' } # => nil

Related: see Querying.

[ GitHub ]

# File 'string.c', line 5090


static VALUE
rb_str_match_m(int argc, VALUE *argv, VALUE str)
{
    VALUE re, result;
    if (argc < 1)
        rb_check_arity(argc, 1, 2);
    re = argv[0];
    argv[0] = str;
    result = rb_funcallv(get_pat(re), rb_intern("match"), argc, argv);
    if (!NIL_P(result) && rb_block_given_p()) {
        return rb_yield(result);
    }
    return result;
}

#match?(pattern, offset = 0) ⇒ `Boolean`

Returns whether a match is found for self and the given arguments; does not update {Regexp Global Variables}.

Computes regexp by converting pattern (if not already a ::Regexp):

regexp = Regexp.new(pattern)

Returns true if self[offset..].match(regexp) returns a ::MatchData object, false otherwise:

'foo'.match?(/o/) # => true
'foo'.match?('o') # => true
'foo'.match?(/x/) # => false
'foo'.match?('f', 1) # => false
'foo'.match?('o', 1) # => true

Related: see Querying.

[ GitHub ]

# File 'string.c', line 5128


static VALUE
rb_str_match_m_p(int argc, VALUE *argv, VALUE str)
{
    VALUE re;
    rb_check_arity(argc, 1, 2);
    re = get_pat(argv[0]);
    return rb_reg_match_p(re, str, argc > 1 ? NUM2LONG(argv[1]) : 0);
}

#next ⇒ `String` Also known as: #succ

Returns the successor to self. The successor is calculated by incrementing characters.

The first character to be incremented is the rightmost alphanumeric: or, if no alphanumerics, the rightmost character:

'THX1138'.succ   # => "THX1139"
'<<koala>>'.succ # => "<<koalb>>"
'***'.succ       # => '**+'
'тест'.succ      # => "тесу"
'こんにちは'.succ  # => "こんにちば"

The successor to a digit is another digit, “carrying” to the next-left character for a “rollover” from 9 to 0, and prepending another digit if necessary:

'00'.succ # => "01"
'09'.succ # => "10"
'99'.succ # => "100"

The successor to a letter is another letter of the same case, carrying to the next-left character for a rollover, and prepending another same-case letter if necessary:

'aa'.succ # => "ab"
'az'.succ # => "ba"
'zz'.succ # => "aaa"
'AA'.succ # => "AB"
'AZ'.succ # => "BA"
'ZZ'.succ # => "AAA"

The successor to a non-alphanumeric character is the next character in the underlying character set’s collating sequence, carrying to the next-left character for a rollover, and prepending another character if necessary:

s = 0.chr * 3   # => "\x00\x00\x00"
s.succ        # => "\x00\x00\x01"
s = 255.chr * 3 # => "\xFF\xFF\xFF"
s.succ        # => "\x01\x00\x00\x00"

Carrying can occur between and among mixtures of alphanumeric characters:

s = 'zz99zz99' # => "zz99zz99"
s.succ         # => "aaa00aa00"
s = '99zz99zz' # => "99zz99zz"
s.succ         # => "100aa00aa"

The successor to an empty String is a new empty String:

''.succ # => ""

Related: see Converting to New String.

[ GitHub ]

# File 'string.c', line 5330


VALUE
rb_str_succ(VALUE orig)
{
    VALUE str;
    str = rb_str_new(RSTRING_PTR(orig), RSTRING_LEN(orig));
    rb_enc_cr_str_copy_for_substr(str, orig);
    return str_succ(str);
}

#next! ⇒ `self` Also known as: #succ!

Like #succ, but modifies self in place; returns self.

Related: see Modifying.

[ GitHub ]

# File 'string.c', line 5436


static VALUE
rb_str_succ_bang(VALUE str)
{
    rb_str_modify(str);
    str_succ(str);
    return str;
}

#oct ⇒ Integer

Interprets the leading substring of self as octal, binary, decimal, or hexadecimal, possibly signed; returns their value as an integer.

In brief:

# Interpreted as octal.
'777'.oct   # => 511
'777x'.oct  # => 511
'0777'.oct  # => 511
'0o777'.oct # => 511
'-777'.oct  # => -511
# Not interpreted as octal.
'0b111'.oct # => 7     # Interpreted as binary.
'0d999'.oct # => 999   # Interpreted as decimal.
'0xfff'.oct # => 4095  # Interpreted as hexadecimal.

The leading substring is interpreted as octal when it begins with:

One or more character representing octal digits (each in the range '0'..'7'); the string to be interpreted ends at the first character that does not represent an octal digit:
```
'7'.oct      @ => 7
'11'.oct     # => 9
'777'.oct    # => 511
'0777'.oct   # => 511
'7778'.oct   # => 511
'777x'.oct   # => 511
```

'0o', followed by one or more octal digits:

'0o777'.oct  # => 511
'0o7778'.oct # => 511

The leading substring is not interpreted as octal when it begins with:

'0b', followed by one or more characters representing binary digits (each in the range '0'..'1'); the string to be interpreted ends at the first character that does not represent a binary digit. the string is interpreted as binary digits (base 2):
```
'0b111'.oct  # => 7
'0b1112'.oct # => 7
```
'0d', followed by one or more characters representing decimal digits (each in the range '0'..'9'); the string to be interpreted ends at the first character that does not represent a decimal digit. the string is interpreted as decimal digits (base 10):
```
'0d999'.oct  # => 999
'0d999x'.oct # => 999
```
'0x', followed by one or more characters representing hexadecimal digits (each in one of the ranges '0'..'9', 'a'..'f', or 'A'..'F'); the string to be interpreted ends at the first character that does not represent a hexadecimal digit. the string is interpreted as hexadecimal digits (base 16):
```
'0xfff'.oct  # => 4095
'0xfffg'.oct # => 4095
```

Any of the above may prefixed with '-', which negates the interpreted value:

'-777'.oct   # => -511
'-0777'.oct  # => -511
'-0b111'.oct # => -7
'-0xfff'.oct # => -4095

For any substring not described above, returns zero:

'foo'.oct      # => 0
''.oct         # => 0

Related: see Converting to Non-String.

[ GitHub ]

# File 'string.c', line 10724


static VALUE
rb_str_oct(VALUE str)
{
    return rb_str_to_inum(str, -8, FALSE);
}

#ord ⇒ Integer

Returns the integer ordinal of the first character of self:

'h'.ord         # => 104
'hello'.ord     # => 104
'тест'.ord      # => 1090
'こんにちは'.ord  # => 12371

Related: see Converting to Non-String.

[ GitHub ]

# File 'string.c', line 10877


static VALUE
rb_str_ord(VALUE s)
{
    unsigned int c;

    c = rb_enc_codepoint(RSTRING_PTR(s), RSTRING_END(s), STR_ENC_GET(s));
    return UINT2NUM(c);
}

#partition(pattern) ⇒ Array, ...

Returns a 3-element array of substrings of self.

If pattern is matched, returns the array:

[pre_match, first_match, post_match]

where:

first_match is the first-found matching substring.
pre_match and post_match are the preceding and following substrings.

If pattern is not matched, returns the array:

[self.dup, "", ""]

Note that in the examples below, a returned string 'hello' is a copy of self, not self.

If pattern is a ::Regexp, performs the equivalent of self.match(pattern) (also setting pattern-matching global variables):

'hello'.partition(/h/)  # => ["", "h", "ello"]
'hello'.partition(/l/)  # => ["he", "l", "lo"]
'hello'.partition(/l+/) # => ["he", "ll", "o"]
'hello'.partition(/o/)  # => ["hell", "o", ""]
'hello'.partition(/^/)  # => ["", "", "hello"]
'hello'.partition(//)   # => ["", "", "hello"]
'hello'.partition(/$/)  # => ["hello", "", ""]
'hello'.partition(/x/)  # => ["hello", "", ""]

If pattern is not a ::Regexp, converts it to a string (if it is not already one), then performs the equivalent of self.index(pattern) (and does not set pattern-matching global variables):

'hello'.partition('h')     # => ["", "h", "ello"]
'hello'.partition('l')     # => ["he", "l", "lo"]
'hello'.partition('ll')    # => ["he", "ll", "o"]
'hello'.partition('o')     # => ["hell", "o", ""]
'hello'.partition('')      # => ["", "", "hello"]
'hello'.partition('x')     # => ["hello", "", ""]
'тест'.partition('т')      # => ["", "т", "ест"]
'こんにちは'.partition('に') # => ["こん", "に", "ちは"]

Related: see Converting to Non-String.

[ GitHub ]

# File 'string.c', line 11090


static VALUE
rb_str_partition(VALUE str, VALUE sep)
{
    long pos;

    sep = get_pat_quoted(sep, 0);
    if (RB_TYPE_P(sep, T_REGEXP)) {
        if (rb_reg_search(sep, str, 0, 0) < 0) {
            goto failed;
        }
        VALUE match = rb_backref_get();
        struct re_registers *regs = RMATCH_REGS(match);

        pos = BEG(0);
        sep = rb_str_subseq(str, pos, END(0) - pos);
    }
    else {
        pos = rb_str_index(str, sep, 0);
        if (pos < 0) goto failed;
    }
    return rb_ary_new3(3, rb_str_subseq(str, 0, pos),
                          sep,
                          rb_str_subseq(str, pos+RSTRING_LEN(sep),
                                             RSTRING_LEN(str)-pos-RSTRING_LEN(sep)));

  failed:
    return rb_ary_new3(3, str_duplicate(rb_cString, str), str_new_empty_String(str), str_new_empty_String(str));
}

#prepend(*other_strings) ⇒ `String`

Prefixes to self the concatenation of the given other_strings; returns self:

'baz'.prepend('foo', 'bar') # => "foobarbaz"

Related: see Modifying.

[ GitHub ]

# File 'string.c', line 4122


static VALUE
rb_str_prepend_multi(int argc, VALUE *argv, VALUE str)
{
    str_modifiable(str);

    if (argc == 1) {
        rb_str_update(str, 0L, 0L, argv[0]);
    }
    else if (argc > 1) {
        int i;
        VALUE arg_str = rb_str_tmp_new(0);
        rb_enc_copy(arg_str, str);
        for (i = 0; i < argc; i++) {
            rb_str_append(arg_str, argv[i]);
        }
        rb_str_update(str, 0L, 0L, arg_str);
    }

    return str;
}

#replace(other_string) ⇒ `self` Also known as: #initialize_copy

Replaces the contents of self with the contents of other_string; returns self:

s = 'foo'        # => "foo"
s.replace('bar') # => "bar"

Related: see Modifying.

[ GitHub ]

# File 'string.c', line 6563


VALUE
rb_str_replace(VALUE str, VALUE str2)
{
    str_modifiable(str);
    if (str == str2) return str;

    StringValue(str2);
    str_discard(str);
    return str_replace(str, str2);
}

#reverse ⇒ `String`

Returns a new string with the characters from self in reverse order.

'drawer'.reverse       # => "reward"
'reviled'.reverse      # => "deliver"
'stressed'.reverse     # => "desserts"
'semordnilaps'.reverse # => "spalindromes"

Related: see Converting to New String.

[ GitHub ]

# File 'string.c', line 6904


static VALUE
rb_str_reverse(VALUE str)
{
    rb_encoding *enc;
    VALUE rev;
    char *s, *e, *p;
    int cr;

    if (RSTRING_LEN(str) <= 1) return str_duplicate(rb_cString, str);
    enc = STR_ENC_GET(str);
    rev = rb_str_new(0, RSTRING_LEN(str));
    s = RSTRING_PTR(str); e = RSTRING_END(str);
    p = RSTRING_END(rev);
    cr = ENC_CODERANGE(str);

    if (RSTRING_LEN(str) > 1) {
        if (single_byte_optimizable(str)) {
            while (s < e) {
                *--p = *s++;
            }
        }
        else if (cr == ENC_CODERANGE_VALID) {
            while (s < e) {
                int clen = rb_enc_fast_mbclen(s, e, enc);

                p -= clen;
                memcpy(p, s, clen);
                s += clen;
            }
        }
        else {
            cr = rb_enc_asciicompat(enc) ?
                ENC_CODERANGE_7BIT : ENC_CODERANGE_VALID;
            while (s < e) {
                int clen = rb_enc_mbclen(s, e, enc);

                if (clen > 1 || (*s & 0x80)) cr = ENC_CODERANGE_UNKNOWN;
                p -= clen;
                memcpy(p, s, clen);
                s += clen;
            }
        }
    }
    STR_SET_LEN(rev, RSTRING_LEN(str));
    str_enc_copy_direct(rev, str);
    ENC_CODERANGE_SET(rev, cr);

    return rev;
}

#reverse! ⇒ `self`

Returns self with its characters reversed:

'drawer'.reverse!       # => "reward"
'reviled'.reverse!      # => "deliver"
'stressed'.reverse!     # => "desserts"
'semordnilaps'.reverse! # => "spalindromes"

Related: see Modifying.

[ GitHub ]

# File 'string.c', line 6969


static VALUE
rb_str_reverse_bang(VALUE str)
{
    if (RSTRING_LEN(str) > 1) {
        if (single_byte_optimizable(str)) {
            char *s, *e, c;

            str_modify_keep_cr(str);
            s = RSTRING_PTR(str);
            e = RSTRING_END(str) - 1;
            while (s < e) {
                c = *s;
                *s++ = *e;
                *e-- = c;
            }
        }
        else {
            str_shared_replace(str, rb_str_reverse(str));
        }
    }
    else {
        str_modify_keep_cr(str);
    }
    return str;
}

#rindex(pattern, offset = self.length) ⇒ Integer^?

Returns the integer position of the last substring that matches the given argument pattern, or nil if none found.

When pattern is a string, returns the index of the last matching substring in self:

'foo'.rindex('f')       # => 0
'foo'.rindex('o')       # => 2
'foo'.rindex('oo'       # => 1
'foo'.rindex('ooo')     # => nil
'тест'.rindex('т')      # => 3
'こんにちは'.rindex('ち') # => 3

When pattern is a ::Regexp, returns the index of the last match in self:

'foo'.rindex(/f/)   # => 0
'foo'.rindex(/o/)   # => 2
'foo'.rindex(/oo/)  # => 1
'foo'.rindex(/ooo/) # => nil

When offset is non-negative, it specifies the maximum starting position in the string to end the search:

'foo'.rindex('o', 0) # => nil
'foo'.rindex('o', 1) # => 1
'foo'.rindex('o', 2) # => 2
'foo'.rindex('o', 3) # => 2

With negative integer argument offset, selects the search position by counting backward from the end of self:

'foo'.rindex('o', -1) # => 2
'foo'.rindex('o', -2) # => 1
'foo'.rindex('o', -3) # => nil
'foo'.rindex('o', -4) # => nil

The last match means starting at the possible last position, not the last of longest matches:

'foo'.rindex(/o+/) # => 2
$~                 # => #<MatchData "o">

To get the last longest match, combine with negative lookbehind:

'foo'.rindex(/(?<!o)o+/) # => 1
$~                       # => #<MatchData "oo">

Or #index with negative lookforward.

'foo'.index(/o+(?!.*o)/) # => 1
$~                       # => #<MatchData "oo">

Related: see Querying.

[ GitHub ]

# File 'string.c', line 4803


static VALUE
rb_str_rindex_m(int argc, VALUE *argv, VALUE str)
{
    VALUE sub;
    VALUE initpos;
    rb_encoding *enc = STR_ENC_GET(str);
    long pos, len = str_strlen(str, enc); /* str's enc */

    if (rb_scan_args(argc, argv, "11", &sub, &initpos) == 2) {
        pos = NUM2LONG(initpos);
        if (pos < 0 && (pos += len) < 0) {
            if (RB_TYPE_P(sub, T_REGEXP)) {
                rb_backref_set(Qnil);
            }
            return Qnil;
        }
        if (pos > len) pos = len;
    }
    else {
        pos = len;
    }

    if (RB_TYPE_P(sub, T_REGEXP)) {
        /* enc = rb_enc_check(str, sub); */
        pos = str_offset(RSTRING_PTR(str), RSTRING_END(str), pos,
                         enc, single_byte_optimizable(str));

        if (rb_reg_search(sub, str, pos, 1) >= 0) {
            VALUE match = rb_backref_get();
            struct re_registers *regs = RMATCH_REGS(match);
            pos = rb_str_sublen(str, BEG(0));
            return LONG2NUM(pos);
        }
    }
    else {
        StringValue(sub);
        pos = rb_str_rindex(str, sub, pos);
        if (pos >= 0) {
            pos = rb_str_sublen(str, pos);
            return LONG2NUM(pos);
        }
    }
    return Qnil;
}

#rjust(width, pad_string = ' ') ⇒ `String`

Returns a right-justified copy of self.

If integer argument width is greater than the size (in characters) of self, returns a new string of length width that is a copy of self, right justified and padded on the left with pad_string:

'hello'.rjust(10)       # => "     hello"
'hello  '.rjust(10)     # => "   hello  "
'hello'.rjust(10, 'ab') # => "ababahello"
'тест'.rjust(10)        # => "      тест"
'こんにちは'.rjust(10)    # => "     こんにちは"

If width <= self.size, returns a copy of self:

'hello'.rjust(5, 'ab')  # => "hello"
'hello'.rjust(1, 'ab')  # => "hello"

Related: see Converting to New String.

[ GitHub ]

# File 'string.c', line 11061


static VALUE
rb_str_rjust(int argc, VALUE *argv, VALUE str)
{
    return rb_str_justify(argc, argv, str, 'r');
}

#rpartition(pattern) ⇒ Array, ...

Returns a 3-element array of substrings of self.

Searches self for a match of pattern, seeking the last match.

If pattern is not matched, returns the array:

["", "", self.dup]

If pattern is matched, returns the array:

[pre_match, last_match, post_match]

where:

last_match is the last-found matching substring.
pre_match and post_match are the preceding and following substrings.

The pattern used is:

pattern itself, if it is a ::Regexp.
Regexp.quote(pattern), if pattern is a string.

Note that in the examples below, a returned string 'hello' is a copy of self, not self.

If pattern is a ::Regexp, searches for the last matching substring (also setting pattern-matching global variables):

'hello'.rpartition(/l/)     # => ["hel", "l", "o"]
'hello'.rpartition(/ll/)    # => ["he", "ll", "o"]
'hello'.rpartition(/h/)     # => ["", "h", "ello"]
'hello'.rpartition(/o/)     # => ["hell", "o", ""]
'hello'.rpartition(//)      # => ["hello", "", ""]
'hello'.rpartition(/x/)     # => ["", "", "hello"]
'тест'.rpartition(/т/)      # => ["тес", "т", ""]
'こんにちは'.rpartition(/に/) # => ["こん", "に", "ちは"]

If pattern is not a ::Regexp, converts it to a string (if it is not already one), then searches for the last matching substring (and does not set pattern-matching global variables):

'hello'.rpartition('l')     # => ["hel", "l", "o"]
'hello'.rpartition('ll')    # => ["he", "ll", "o"]
'hello'.rpartition('h')     # => ["", "h", "ello"]
'hello'.rpartition('o')     # => ["hell", "o", ""]
'hello'.rpartition('')      # => ["hello", "", ""]
'тест'.rpartition('т')      # => ["тес", "т", ""]
'こんにちは'.rpartition('に') # => ["こん", "に", "ちは"]

Related: see Converting to Non-String.

[ GitHub ]

# File 'string.c', line 11127


static VALUE
rb_str_rpartition(VALUE str, VALUE sep)
{
    long pos = RSTRING_LEN(str);

    sep = get_pat_quoted(sep, 0);
    if (RB_TYPE_P(sep, T_REGEXP)) {
        if (rb_reg_search(sep, str, pos, 1) < 0) {
            goto failed;
        }
        VALUE match = rb_backref_get();
        struct re_registers *regs = RMATCH_REGS(match);

        pos = BEG(0);
        sep = rb_str_subseq(str, pos, END(0) - pos);
    }
    else {
        pos = rb_str_sublen(str, pos);
        pos = rb_str_rindex(str, sep, pos);
        if (pos < 0) {
            goto failed;
        }
    }

    return rb_ary_new3(3, rb_str_subseq(str, 0, pos),
                          sep,
                          rb_str_subseq(str, pos+RSTRING_LEN(sep),
                                        RSTRING_LEN(str)-pos-RSTRING_LEN(sep)));
  failed:
    return rb_ary_new3(3, str_new_empty_String(str), str_new_empty_String(str), str_duplicate(rb_cString, str));
}

#rstrip ⇒ `String`

Returns a copy of self with trailing whitespace removed; see Whitespace in Strings:

whitespace = "\x00\t\n\v\f\r "
s = whitespace + 'abc' + whitespace
s        # => "\u0000\t\n\v\f\r abc\u0000\t\n\v\f\r "
s.rstrip # => "\u0000\t\n\v\f\r abc"

Related: see Converting to New String.

[ GitHub ]

# File 'string.c', line 10407


static VALUE
rb_str_rstrip(VALUE str)
{
    rb_encoding *enc;
    char *start;
    long olen, roffset;

    enc = STR_ENC_GET(str);
    RSTRING_GETMEM(str, start, olen);
    roffset = rstrip_offset(str, start, start+olen, enc);

    if (roffset <= 0) return str_duplicate(rb_cString, str);
    return rb_str_subseq(str, 0, olen-roffset);
}

#rstrip! ⇒ `self`^?

Like #rstrip, except that:

Performs stripping in self (not in a copy of self).
Returns self if any characters are stripped, nil otherwise.

Related: see Modifying.

[ GitHub ]

# File 'string.c', line 10370


static VALUE
rb_str_rstrip_bang(VALUE str)
{
    rb_encoding *enc;
    char *start;
    long olen, roffset;

    str_modify_keep_cr(str);
    enc = STR_ENC_GET(str);
    RSTRING_GETMEM(str, start, olen);
    roffset = rstrip_offset(str, start, start+olen, enc);
    if (roffset > 0) {
        long len = olen - roffset;

        STR_SET_LEN(str, len);
        TERM_FILL(start+len, rb_enc_mbminlen(enc));
        return str;
    }
    return Qnil;
}

#scan(pattern) ⇒ `array_of_results` #scan(pattern) {|result| ... } ⇒ `self`

Matches a pattern against self:

If pattern is a ::Regexp, the pattern used is pattern itself.
If pattern is a string, the pattern used is Regexp.quote(pattern).

Generates a collection of matching results and updates regexp-related global variables:

If the pattern contains no groups, each result is a matched substring.
If the pattern contains groups, each result is an array containing a matched substring for each group.

With no block given, returns an array of the results:

'cruel world'.scan(/\w+/)      # => ["cruel", "world"]
'cruel world'.scan(/.../)      # => ["cru", "el ", "wor"]
'cruel world'.scan(/(...)/)    # => [["cru"], ["el "], ["wor"]]
'cruel world'.scan(/(..)(..)/) # => [["cr", "ue"], ["l ", "wo"]]
'тест'.scan(/../)              # => ["те", "ст"]
'こんにちは'.scan(/../)         # => ["こん", "にち"]
'abracadabra'.scan('ab')       # => ["ab", "ab"]
'abracadabra'.scan('nosuch')   # => []

With a block given, calls the block with each result; returns self:

'cruel world'.scan(/\w+/) {|w| p w }
# => "cruel"
# => "world"
'cruel world'.scan(/(.)(.)/) {|x, y| p [x, y] }
# => ["c", "r"]
# => ["u", "e"]
# => ["l", " "]
# => ["w", "o"]
# => ["r", "l"]

Related: see Converting to Non-String.

[ GitHub ]

# File 'string.c', line 10558


static VALUE
rb_str_scan(VALUE str, VALUE pat)
{
    VALUE result;
    long start = 0;
    long last = -1, prev = 0;
    char *p = RSTRING_PTR(str); long len = RSTRING_LEN(str);

    pat = get_pat_quoted(pat, 1);
    mustnot_broken(str);
    if (!rb_block_given_p()) {
        VALUE ary = rb_ary_new();

        while (!NIL_P(result = scan_once(str, pat, &start, 0))) {
            last = prev;
            prev = start;
            rb_ary_push(ary, result);
        }
        if (last >= 0) rb_pat_search(pat, str, last, 1);
        else rb_backref_set(Qnil);
        return ary;
    }

    while (!NIL_P(result = scan_once(str, pat, &start, 1))) {
        last = prev;
        prev = start;
        rb_yield(result);
        str_mod_check(str, p, len);
    }
    if (last >= 0) rb_pat_search(pat, str, last, 1);
    return str;
}

#scrub(replacement_string = default_replacement_string) ⇒ `String` #scrub {|sequence| ... } ⇒ `String`

Returns a copy of self with each invalid byte sequence replaced by the given replacement_string.

With no block given, replaces each invalid sequence with the given default_replacement_string (by default, "�" for a Unicode encoding, '?' otherwise):

"foo\x81\x81bar"scrub                             # => "foo��bar"
"foo\x81\x81bar".force_encoding('US-ASCII').scrub # => "foo??bar"
"foo\x81\x81bar".scrub('xyzzy')                   # => "fooxyzzyxyzzybar"

With a block given, calls the block with each invalid sequence, and replaces that sequence with the return value of the block:

"foo\x81\x81bar".scrub {|sequence| p sequence; 'XYZZY' } # => "fooXYZZYXYZZYbar"

Output :

"\x81"
"\x81"

Related: see Converting to New String.

[ GitHub ]

# File 'string.c', line 11872


static VALUE
str_scrub(int argc, VALUE *argv, VALUE str)
{
    VALUE repl = argc ? (rb_check_arity(argc, 0, 1), argv[0]) : Qnil;
    VALUE new = rb_str_scrub(str, repl);
    return NIL_P(new) ? str_duplicate(rb_cString, str): new;
}

#scrub!(replacement_string = default_replacement_string) ⇒ `self` #scrub! {|sequence| ... } ⇒ `self`

Like #scrub, except that:

Any replacements are made in self.
Returns self.

Related: see Modifying.

[ GitHub ]

# File 'string.c', line 11893


static VALUE
str_scrub_bang(int argc, VALUE *argv, VALUE str)
{
    VALUE repl = argc ? (rb_check_arity(argc, 0, 1), argv[0]) : Qnil;
    VALUE new = rb_str_scrub(str, repl);
    if (!NIL_P(new)) rb_str_replace(str, new);
    return str;
}

#setbyte(index, integer) ⇒ Integer

Sets the byte at zero-based offset #index to the value of the given integer; returns integer:

s = 'xyzzy'
s.setbyte(2, 129) # => 129
s                 # => "xy\x81zy"

Related: see Modifying.

[ GitHub ]

# File 'string.c', line 6648


VALUE
rb_str_setbyte(VALUE str, VALUE index, VALUE value)
{
    long pos = NUM2LONG(index);
    long len = RSTRING_LEN(str);
    char *ptr, *head, *left = 0;
    rb_encoding *enc;
    int cr = ENC_CODERANGE_UNKNOWN, width, nlen;

    if (pos < -len || len <= pos)
        rb_raise(rb_eIndexError, "index %ld out of string", pos);
    if (pos < 0)
        pos += len;

    VALUE v = rb_to_int(value);
    VALUE w = rb_int_and(v, INT2FIX(0xff));
    char byte = (char)(NUM2INT(w) & 0xFF);

    if (!str_independent(str))
        str_make_independent(str);
    enc = STR_ENC_GET(str);
    head = RSTRING_PTR(str);
    ptr = &head[pos];
    if (!STR_EMBED_P(str)) {
        cr = ENC_CODERANGE(str);
        switch (cr) {
          case ENC_CODERANGE_7BIT:
            left = ptr;
            *ptr = byte;
            if (ISASCII(byte)) goto end;
            nlen = rb_enc_precise_mbclen(left, head+len, enc);
            if (!MBCLEN_CHARFOUND_P(nlen))
                ENC_CODERANGE_SET(str, ENC_CODERANGE_BROKEN);
            else
                ENC_CODERANGE_SET(str, ENC_CODERANGE_VALID);
            goto end;
          case ENC_CODERANGE_VALID:
            left = rb_enc_left_char_head(head, ptr, head+len, enc);
            width = rb_enc_precise_mbclen(left, head+len, enc);
            *ptr = byte;
            nlen = rb_enc_precise_mbclen(left, head+len, enc);
            if (!MBCLEN_CHARFOUND_P(nlen))
                ENC_CODERANGE_SET(str, ENC_CODERANGE_BROKEN);
            else if (MBCLEN_CHARFOUND_LEN(nlen) != width || ISASCII(byte))
                ENC_CODERANGE_CLEAR(str);
            goto end;
        }
    }
    ENC_CODERANGE_CLEAR(str);
    *ptr = byte;

  end:
    return value;
}

#length ⇒ Integer #size ⇒ Integer

Alias for #length.

#[](index) ⇒ `String`^? #[](start, length) ⇒ `String`^? #[](range) ⇒ `String`^? #[](substring) ⇒ `String`^?

Alias for #[].

#slice!(index) ⇒ `String`^? #slice!(start, length) ⇒ `String`^? #slice!(range) ⇒ `String`^? #slice!(regexp, capture = 0) ⇒ `String`^? #slice!(substring) ⇒ `String`^?

Like #[] (and its alias #slice), except that:

Performs substitutions in self (not in a copy of self).
Returns the removed substring if any modifications were made, nil otherwise.

A few examples:

s = 'hello'
s.slice!('e') # => "e"
s             # => "hllo"
s.slice!('e') # => nil
s             # => "hllo"

Related: see Modifying.

[ GitHub ]

# File 'string.c', line 6028


static VALUE
rb_str_slice_bang(int argc, VALUE *argv, VALUE str)
{
    VALUE result = Qnil;
    VALUE indx;
    long beg, len = 1;
    char *p;

    rb_check_arity(argc, 1, 2);
    str_modify_keep_cr(str);
    indx = argv[0];
    if (RB_TYPE_P(indx, T_REGEXP)) {
        if (rb_reg_search(indx, str, 0, 0) < 0) return Qnil;
        VALUE match = rb_backref_get();
        struct re_registers *regs = RMATCH_REGS(match);
        int nth = 0;
        if (argc > 1 && (nth = rb_reg_backref_number(match, argv[1])) < 0) {
            if ((nth += regs->num_regs) <= 0) return Qnil;
        }
        else if (nth >= regs->num_regs) return Qnil;
        beg = BEG(nth);
        len = END(nth) - beg;
        goto subseq;
    }
    else if (argc == 2) {
        beg = NUM2LONG(indx);
        len = NUM2LONG(argv[1]);
        goto num_index;
    }
    else if (FIXNUM_P(indx)) {
        beg = FIX2LONG(indx);
        if (!(p = rb_str_subpos(str, beg, &len))) return Qnil;
        if (!len) return Qnil;
        beg = p - RSTRING_PTR(str);
        goto subseq;
    }
    else if (RB_TYPE_P(indx, T_STRING)) {
        beg = rb_str_index(str, indx, 0);
        if (beg == -1) return Qnil;
        len = RSTRING_LEN(indx);
        result = str_duplicate(rb_cString, indx);
        goto squash;
    }
    else {
        switch (rb_range_beg_len(indx, &beg, &len, str_strlen(str, NULL), 0)) {
          case Qnil:
            return Qnil;
          case Qfalse:
            beg = NUM2LONG(indx);
            if (!(p = rb_str_subpos(str, beg, &len))) return Qnil;
            if (!len) return Qnil;
            beg = p - RSTRING_PTR(str);
            goto subseq;
          default:
            goto num_index;
        }
    }

  num_index:
    if (!(p = rb_str_subpos(str, beg, &len))) return Qnil;
    beg = p - RSTRING_PTR(str);

  subseq:
    result = rb_str_new(RSTRING_PTR(str)+beg, len);
    rb_enc_cr_str_copy_for_substr(result, str);

  squash:
    if (len > 0) {
        if (beg == 0) {
            rb_str_drop_bytes(str, len);
        }
        else {
            char *sptr = RSTRING_PTR(str);
            long slen = RSTRING_LEN(str);
            if (beg + len > slen) /* pathological check */
                len = slen - beg;
            memmove(sptr + beg,
                    sptr + beg + len,
                    slen - (beg + len));
            slen -= len;
            STR_SET_LEN(str, slen);
            TERM_FILL(&sptr[slen], TERM_LEN(str));
        }
    }
    return result;
}

#split(field_sep = $;, limit = 0) ⇒ `String` #split(field_sep = $;, limit = 0) {|substring| ... } ⇒ `self`

Creates an array of substrings by splitting self at each occurrence of the given field separator field_sep.

With no arguments given, splits using the field separator $;, whose default value is nil.

With no block given, returns the array of substrings:

'abracadabra'.split('a') # => ["", "br", "c", "d", "br"]

When field_sep is nil or ' ' (a single space), splits at each sequence of whitespace:

'foo bar baz'.split(nil)          # => ["foo", "bar", "baz"]
'foo bar baz'.split(' ')          # => ["foo", "bar", "baz"]
"foo \n\tbar\t\n  baz".split(' ') # => ["foo", "bar", "baz"]
'foo  bar   baz'.split(' ')       # => ["foo", "bar", "baz"]
''.split(' ')                     # => []

When field_sep is an empty string, splits at every character:

'abracadabra'.split('') # => ["a", "b", "r", "a", "c", "a", "d", "a", "b", "r", "a"]
''.split('')            # => []
'тест'.split('')        # => ["т", "е", "с", "т"]
'こんにちは'.split('')   # => ["こ", "ん", "に", "ち", "は"]

When field_sep is a non-empty string and different from ' ' (a single space), uses that string as the separator:

'abracadabra'.split('a')  # => ["", "br", "c", "d", "br"]
'abracadabra'.split('ab') # => ["", "racad", "ra"]
''.split('a')             # => []
'тест'.split('т')         # => ["", "ес"]
'こんにちは'.split('に')    # => ["こん", "ちは"]

When field_sep is a ::Regexp, splits at each occurrence of a matching substring:

'abracadabra'.split(/ab/) # => ["", "racad", "ra"]
'1 + 1 == 2'.split(/\W+/) # => ["1", "1", "2"]
'abracadabra'.split(//)   # => ["a", "b", "r", "a", "c", "a", "d", "a", "b", "r", "a"]

If the Regexp contains groups, their matches are included in the returned array:

'1:2:3'.split(/(:)()()/, 2) # => ["1", ":", "", "", "2:3"]

Argument limit sets a limit on the size of the returned array; it also determines whether trailing empty strings are included in the returned array.

When limit is zero, there is no limit on the size of the array, but trailing empty strings are omitted:

'abracadabra'.split('', 0)  # => ["a", "b", "r", "a", "c", "a", "d", "a", "b", "r", "a"]
'abracadabra'.split('a', 0) # => ["", "br", "c", "d", "br"]  # Empty string after last 'a' omitted.

When limit is a positive integer, there is a limit on the size of the array (no more than n - 1 splits occur), and trailing empty strings are included:

'abracadabra'.split('', 3)   # => ["a", "b", "racadabra"]
'abracadabra'.split('a', 3)  # => ["", "br", "cadabra"]
'abracadabra'.split('', 30)  # => ["a", "b", "r", "a", "c", "a", "d", "a", "b", "r", "a", ""]
'abracadabra'.split('a', 30) # => ["", "br", "c", "d", "br", ""]
'abracadabra'.split('', 1)   # => ["abracadabra"]
'abracadabra'.split('a', 1)  # => ["abracadabra"]

When limit is negative, there is no limit on the size of the array, and trailing empty strings are omitted:

'abracadabra'.split('', -1)  # => ["a", "b", "r", "a", "c", "a", "d", "a", "b", "r", "a", ""]
'abracadabra'.split('a', -1) # => ["", "br", "c", "d", "br", ""]

If a block is given, it is called with each substring and returns self:

'foo bar baz'.split(' ') {|substring| p substring }

Output :

"foo"
"bar"
"baz"

Note that the above example is functionally equivalent to:

'foo bar baz'.split(' ').each {|substring| p substring }

Output :

"foo"
"bar"
"baz"

But the latter:

Has poorer performance because it creates an intermediate array.
Returns an array (instead of self).

Related: see Converting to Non-String.

[ GitHub ]

# File 'string.c', line 9160


static VALUE
rb_str_split_m(int argc, VALUE *argv, VALUE str)
{
    rb_encoding *enc;
    VALUE spat;
    VALUE limit;
    split_type_t split_type;
    long beg, end, i = 0, empty_count = -1;
    int lim = 0;
    VALUE result, tmp;

    result = rb_block_given_p() ? Qfalse : Qnil;
    if (rb_scan_args(argc, argv, "02", &spat, &limit) == 2) {
        lim = NUM2INT(limit);
        if (lim <= 0) limit = Qnil;
        else if (lim == 1) {
            if (RSTRING_LEN(str) == 0)
                return result ? rb_ary_new2(0) : str;
            tmp = str_duplicate(rb_cString, str);
            if (!result) {
                rb_yield(tmp);
                return str;
            }
            return rb_ary_new3(1, tmp);
        }
        i = 1;
    }
    if (NIL_P(limit) && !lim) empty_count = 0;

    enc = STR_ENC_GET(str);
    split_type = SPLIT_TYPE_REGEXP;
    if (!NIL_P(spat)) {
        spat = get_pat_quoted(spat, 0);
    }
    else if (NIL_P(spat = rb_fs)) {
        split_type = SPLIT_TYPE_AWK;
    }
    else if (!(spat = rb_fs_check(spat))) {
        rb_raise(rb_eTypeError, "value of $; must be String or Regexp");
    }
    else {
        rb_category_warn(RB_WARN_CATEGORY_DEPRECATED, "$; is set to non-nil value");
    }
    if (split_type != SPLIT_TYPE_AWK) {
        switch (BUILTIN_TYPE(spat)) {
          case T_REGEXP:
            rb_reg_options(spat); /* check if uninitialized */
            tmp = RREGEXP_SRC(spat);
            split_type = literal_split_pattern(tmp, SPLIT_TYPE_REGEXP);
            if (split_type == SPLIT_TYPE_AWK) {
                spat = tmp;
                split_type = SPLIT_TYPE_STRING;
            }
            break;

          case T_STRING:
            mustnot_broken(spat);
            split_type = literal_split_pattern(spat, SPLIT_TYPE_STRING);
            break;

          default:
            UNREACHABLE_RETURN(Qnil);
        }
    }

#define SPLIT_STR(beg, len) ( \
        empty_count = split_string(result, str, beg, len, empty_count), \
        str_mod_check(str, str_start, str_len))

    beg = 0;
    char *ptr = RSTRING_PTR(str);
    char *const str_start = ptr;
    const long str_len = RSTRING_LEN(str);
    char *const eptr = str_start + str_len;
    if (split_type == SPLIT_TYPE_AWK) {
        char *bptr = ptr;
        int skip = 1;
        unsigned int c;

        if (result) result = rb_ary_new();
        end = beg;
        if (is_ascii_string(str)) {
            while (ptr < eptr) {
                c = (unsigned char)*ptr++;
                if (skip) {
                    if (ascii_isspace(c)) {
                        beg = ptr - bptr;
                    }
                    else {
                        end = ptr - bptr;
                        skip = 0;
                        if (!NIL_P(limit) && lim <= i) break;
                    }
                }
                else if (ascii_isspace(c)) {
                    SPLIT_STR(beg, end-beg);
                    skip = 1;
                    beg = ptr - bptr;
                    if (!NIL_P(limit)) ++i;
                }
                else {
                    end = ptr - bptr;
                }
            }
        }
        else {
            while (ptr < eptr) {
                int n;

                c = rb_enc_codepoint_len(ptr, eptr, &n, enc);
                ptr += n;
                if (skip) {
                    if (rb_isspace(c)) {
                        beg = ptr - bptr;
                    }
                    else {
                        end = ptr - bptr;
                        skip = 0;
                        if (!NIL_P(limit) && lim <= i) break;
                    }
                }
                else if (rb_isspace(c)) {
                    SPLIT_STR(beg, end-beg);
                    skip = 1;
                    beg = ptr - bptr;
                    if (!NIL_P(limit)) ++i;
                }
                else {
                    end = ptr - bptr;
                }
            }
        }
    }
    else if (split_type == SPLIT_TYPE_STRING) {
        char *substr_start = ptr;
        char *sptr = RSTRING_PTR(spat);
        long slen = RSTRING_LEN(spat);

        if (result) result = rb_ary_new();
        mustnot_broken(str);
        enc = rb_enc_check(str, spat);
        while (ptr < eptr &&
               (end = rb_memsearch(sptr, slen, ptr, eptr - ptr, enc)) >= 0) {
            /* Check we are at the start of a char */
            char *t = rb_enc_right_char_head(ptr, ptr + end, eptr, enc);
            if (t != ptr + end) {
                ptr = t;
                continue;
            }
            SPLIT_STR(substr_start - str_start, (ptr+end) - substr_start);
            str_mod_check(spat, sptr, slen);
            ptr += end + slen;
            substr_start = ptr;
            if (!NIL_P(limit) && lim <= ++i) break;
        }
        beg = ptr - str_start;
    }
    else if (split_type == SPLIT_TYPE_CHARS) {
        int n;

        if (result) result = rb_ary_new_capa(RSTRING_LEN(str));
        mustnot_broken(str);
        enc = rb_enc_get(str);
        while (ptr < eptr &&
               (n = rb_enc_precise_mbclen(ptr, eptr, enc)) > 0) {
            SPLIT_STR(ptr - str_start, n);
            ptr += n;
            if (!NIL_P(limit) && lim <= ++i) break;
        }
        beg = ptr - str_start;
    }
    else {
        if (result) result = rb_ary_new();
        long len = RSTRING_LEN(str);
        long start = beg;
        long idx;
        int last_null = 0;
        struct re_registers *regs;
        VALUE match = 0;

        for (; rb_reg_search(spat, str, start, 0) >= 0;
             (match ? (rb_match_unbusy(match), rb_backref_set(match)) : (void)0)) {
            match = rb_backref_get();
            if (!result) rb_match_busy(match);
            regs = RMATCH_REGS(match);
            end = BEG(0);
            if (start == end && BEG(0) == END(0)) {
                if (!ptr) {
                    SPLIT_STR(0, 0);
                    break;
                }
                else if (last_null == 1) {
                    SPLIT_STR(beg, rb_enc_fast_mbclen(ptr+beg, eptr, enc));
                    beg = start;
                }
                else {
                    if (start == len)
                        start++;
                    else
                        start += rb_enc_fast_mbclen(ptr+start,eptr,enc);
                    last_null = 1;
                    continue;
                }
            }
            else {
                SPLIT_STR(beg, end-beg);
                beg = start = END(0);
            }
            last_null = 0;

            for (idx=1; idx < regs->num_regs; idx++) {
                if (BEG(idx) == -1) continue;
                SPLIT_STR(BEG(idx), END(idx)-BEG(idx));
            }
            if (!NIL_P(limit) && lim <= ++i) break;
        }
        if (match) rb_match_unbusy(match);
    }
    if (RSTRING_LEN(str) > 0 && (!NIL_P(limit) || RSTRING_LEN(str) > beg || lim < 0)) {
        SPLIT_STR(beg, RSTRING_LEN(str)-beg);
    }

    return result ? result : str;
}

#squeeze(*selectors) ⇒ `String`

Returns a copy of self with each tuple (doubling, tripling, etc.) of specified characters “squeezed” down to a single character.

The tuples to be squeezed are specified by arguments selectors, each of which is a string; see Character Selectors.

A single argument may be a single character:

'Noooooo!'.squeeze('o')      # => "No!"
'foo  bar  baz'.squeeze(' ') # => "foo bar baz"
'Mississippi'.squeeze('s')   # => "Misisippi"
'Mississippi'.squeeze('p')   # => "Mississipi"
'Mississippi'.squeeze('x')   # => "Mississippi"  # Unused selector character is ignored.
'бессонница'.squeeze('с')    # => "бесонница"
'бессонница'.squeeze('н')    # => "бессоница"

A single argument may be a string of characters:

'Mississippi'.squeeze('sp')       # => "Misisipi"
'Mississippi'.squeeze('ps')       # => "Misisipi"   # Order doesn't matter.
'Mississippi'.squeeze('nonsense') # => "Misisippi"  # Unused selector characters are ignored.

A single argument may be a range of characters:

'Mississippi'.squeeze('a-p') # => "Mississipi"
'Mississippi'.squeeze('q-z') # => "Misisippi"
'Mississippi'.squeeze('a-z') # => "Misisipi"

Multiple arguments are allowed; see Multiple Character Selectors.

Related: see Converting to New String.

[ GitHub ]

# File 'string.c', line 8936


static VALUE
rb_str_squeeze(int argc, VALUE *argv, VALUE str)
{
    str = str_duplicate(rb_cString, str);
    rb_str_squeeze_bang(argc, argv, str);
    return str;
}

#squeeze!(*selectors) ⇒ `self`^?

Like #squeeze, except that:

Characters are squeezed in self (not in a copy of self).
Returns self if any changes are made, nil otherwise.

Related: See Modifying.

[ GitHub ]

# File 'string.c', line 8852


static VALUE
rb_str_squeeze_bang(int argc, VALUE *argv, VALUE str)
{
    char squeez[TR_TABLE_SIZE];
    rb_encoding *enc = 0;
    VALUE del = 0, nodel = 0;
    unsigned char *s, *send, *t;
    int i, modify = 0;
    int ascompat, singlebyte = single_byte_optimizable(str);
    unsigned int save;

    if (argc == 0) {
        enc = STR_ENC_GET(str);
    }
    else {
        for (i=0; i<argc; i++) {
            VALUE s = argv[i];

            StringValue(s);
            enc = rb_enc_check(str, s);
            if (singlebyte && !single_byte_optimizable(s))
                singlebyte = 0;
            tr_setup_table(s, squeez, i==0, &del, &nodel, enc);
        }
    }

    str_modify_keep_cr(str);
    s = t = (unsigned char *)RSTRING_PTR(str);
    if (!s || RSTRING_LEN(str) == 0) return Qnil;
    send = (unsigned char *)RSTRING_END(str);
    save = -1;
    ascompat = rb_enc_asciicompat(enc);

    if (singlebyte) {
        while (s < send) {
            unsigned int c = *s++;
            if (c != save || (argc > 0 && !squeez[c])) {
                *t++ = save = c;
            }
        }
    }
    else {
        while (s < send) {
            unsigned int c;
            int clen;

            if (ascompat && (c = *s) < 0x80) {
                if (c != save || (argc > 0 && !squeez[c])) {
                    *t++ = save = c;
                }
                s++;
            }
            else {
                c = rb_enc_codepoint_len((char *)s, (char *)send, &clen, enc);

                if (c != save || (argc > 0 && !tr_find(c, squeez, del, nodel))) {
                    if (t != s) rb_enc_mbcput(c, t, enc);
                    save = c;
                    t += clen;
                }
                s += clen;
            }
        }
    }

    TERM_FILL((char *)t, TERM_LEN(str));
    if ((char *)t - RSTRING_PTR(str) != RSTRING_LEN(str)) {
        STR_SET_LEN(str, (char *)t - RSTRING_PTR(str));
        modify = 1;
    }

    if (modify) return str;
    return Qnil;
}

#start_with?(*patterns) ⇒ `Boolean`

Returns whether self starts with any of the given patterns.

For each argument, the pattern used is:

The pattern itself, if it is a ::Regexp.
Regexp.quote(pattern), if it is a string.

Returns true if any pattern matches the beginning, false otherwise:

'hello'.start_with?('hell')               # => true
'hello'.start_with?(/H/i)                 # => true
'hello'.start_with?('heaven', 'hell')     # => true
'hello'.start_with?('heaven', 'paradise') # => false
'тест'.start_with?('т')                   # => true
'こんにちは'.start_with?('こ')              # => true

Related: see Querying.

[ GitHub ]

# File 'string.c', line 11167


static VALUE
rb_str_start_with(int argc, VALUE *argv, VALUE str)
{
    int i;

    for (i=0; i<argc; i++) {
        VALUE tmp = argv[i];
        if (RB_TYPE_P(tmp, T_REGEXP)) {
            if (rb_reg_start_with_p(tmp, str))
                return Qtrue;
        }
        else {
            const char *p, *s, *e;
            long slen, tlen;
            rb_encoding *enc;

            StringValue(tmp);
            enc = rb_enc_check(str, tmp);
            if ((tlen = RSTRING_LEN(tmp)) == 0) return Qtrue;
            if ((slen = RSTRING_LEN(str)) < tlen) continue;
            p = RSTRING_PTR(str);
            e = p + slen;
            s = p + tlen;
            if (!at_char_right_boundary(p, s, e, enc))
                continue;
            if (memcmp(p, RSTRING_PTR(tmp), tlen) == 0)
                return Qtrue;
        }
    }
    return Qfalse;
}

#strip ⇒ `String`

Returns a copy of self with leading and trailing whitespace removed; see Whitespace in Strings:

whitespace = "\x00\t\n\v\f\r "
s = whitespace + 'abc' + whitespace
# => "\u0000\t\n\v\f\r abc\u0000\t\n\v\f\r "
s.strip # => "abc"

Related: see Converting to New String.

[ GitHub ]

# File 'string.c', line 10477


static VALUE
rb_str_strip(VALUE str)
{
    char *start;
    long olen, loffset, roffset;
    rb_encoding *enc = STR_ENC_GET(str);

    RSTRING_GETMEM(str, start, olen);
    loffset = lstrip_offset(str, start, start+olen, enc);
    roffset = rstrip_offset(str, start+loffset, start+olen, enc);

    if (loffset <= 0 && roffset <= 0) return str_duplicate(rb_cString, str);
    return rb_str_subseq(str, loffset, olen-loffset-roffset);
}

#strip! ⇒ `self`^?

Like #strip, except that:

Any modifications are made to self.
Returns self if any modification are made, nil otherwise.

Related: see Modifying.

[ GitHub ]

# File 'string.c', line 10435


static VALUE
rb_str_strip_bang(VALUE str)
{
    char *start;
    long olen, loffset, roffset;
    rb_encoding *enc;

    str_modify_keep_cr(str);
    enc = STR_ENC_GET(str);
    RSTRING_GETMEM(str, start, olen);
    loffset = lstrip_offset(str, start, start+olen, enc);
    roffset = rstrip_offset(str, start+loffset, start+olen, enc);

    if (loffset > 0 || roffset > 0) {
        long len = olen-roffset;
        if (loffset > 0) {
            len -= loffset;
            memmove(start, start + loffset, len);
        }
        STR_SET_LEN(str, len);
        TERM_FILL(start+len, rb_enc_mbminlen(enc));
        return str;
    }
    return Qnil;
}

#sub(pattern, replacement) ⇒ `String` #sub(pattern) {|match| ... } ⇒ `String`

Returns a copy of self, possibly with a substring replaced.

Argument pattern may be a string or a Regexp; argument replacement may be a string or a ::Hash.

Varying types for the argument values makes this method very versatile.

Below are some simple examples; for many more examples, see Substitution Methods.

With arguments pattern and string replacement given, replaces the first matching substring with the given replacement string:

s = 'abracadabra'       # => "abracadabra"
s.sub('bra', 'xyzzy')   # => "axyzzycadabra"
s.sub(/bra/, 'xyzzy')   # => "axyzzycadabra"
s.sub('nope', 'xyzzy')  # => "abracadabra"

With arguments pattern and hash replacement given, replaces the first matching substring with a value from the given replacement hash, or removes it:

h = {'a' => 'A', 'b' => 'B', 'c' => 'C'}
s.sub('b', h)  # => "aBracadabra"
s.sub(/b/, h)  # => "aBracadabra"
s.sub(/d/, h)  # => "abracaabra"  # 'd' removed.

With argument pattern and a block given, calls the block with each matching substring; replaces that substring with the block’s return value:

s.sub('b') {|match| match.upcase } # => "aBracadabra"

Related: see Converting to New String.

[ GitHub ]

# File 'string.c', line 6326


static VALUE
rb_str_sub(int argc, VALUE *argv, VALUE str)
{
    str = str_duplicate(rb_cString, str);
    rb_str_sub_bang(argc, argv, str);
    return str;
}

#sub!(pattern, replacement) ⇒ `self`^? #sub!(pattern) {|match| ... } ⇒ `self`^?

Like #sub, except that:

Changes are made to self, not to copy of self.
Returns self if any changes are made, nil otherwise.

Related: see Modifying.

[ GitHub ]

# File 'string.c', line 6207


static VALUE
rb_str_sub_bang(int argc, VALUE *argv, VALUE str)
{
    VALUE pat, repl, hash = Qnil;
    int iter = 0;
    long plen;
    int min_arity = rb_block_given_p() ? 1 : 2;
    long beg;

    rb_check_arity(argc, min_arity, 2);
    if (argc == 1) {
        iter = 1;
    }
    else {
        repl = argv[1];
        hash = rb_check_hash_type(argv[1]);
        if (NIL_P(hash)) {
            StringValue(repl);
        }
    }

    pat = get_pat_quoted(argv[0], 1);

    str_modifiable(str);
    beg = rb_pat_search(pat, str, 0, 1);
    if (beg >= 0) {
        rb_encoding *enc;
        int cr = ENC_CODERANGE(str);
        long beg0, end0;
        VALUE match, match0 = Qnil;
        struct re_registers *regs;
        char *p, *rp;
        long len, rlen;

        match = rb_backref_get();
        regs = RMATCH_REGS(match);
        if (RB_TYPE_P(pat, T_STRING)) {
            beg0 = beg;
            end0 = beg0 + RSTRING_LEN(pat);
            match0 = pat;
        }
        else {
            beg0 = BEG(0);
            end0 = END(0);
            if (iter) match0 = rb_reg_nth_match(0, match);
        }

        if (iter || !NIL_P(hash)) {
            p = RSTRING_PTR(str); len = RSTRING_LEN(str);

            if (iter) {
                repl = rb_obj_as_string(rb_yield(match0));
            }
            else {
                repl = rb_hash_aref(hash, rb_str_subseq(str, beg0, end0 - beg0));
                repl = rb_obj_as_string(repl);
            }
            str_mod_check(str, p, len);
            rb_check_frozen(str);
        }
        else {
            repl = rb_reg_regsub(repl, str, regs, RB_TYPE_P(pat, T_STRING) ? Qnil : pat);
        }

        enc = rb_enc_compatible(str, repl);
        if (!enc) {
            rb_encoding *str_enc = STR_ENC_GET(str);
            p = RSTRING_PTR(str); len = RSTRING_LEN(str);
            if (coderange_scan(p, beg0, str_enc) != ENC_CODERANGE_7BIT ||
                coderange_scan(p+end0, len-end0, str_enc) != ENC_CODERANGE_7BIT) {
                rb_raise(rb_eEncCompatError, "incompatible character encodings: %s and %s",
                         rb_enc_inspect_name(str_enc),
                         rb_enc_inspect_name(STR_ENC_GET(repl)));
            }
            enc = STR_ENC_GET(repl);
        }
        rb_str_modify(str);
        rb_enc_associate(str, enc);
        if (ENC_CODERANGE_UNKNOWN < cr && cr < ENC_CODERANGE_BROKEN) {
            int cr2 = ENC_CODERANGE(repl);
            if (cr2 == ENC_CODERANGE_BROKEN ||
                (cr == ENC_CODERANGE_VALID && cr2 == ENC_CODERANGE_7BIT))
                cr = ENC_CODERANGE_UNKNOWN;
            else
                cr = cr2;
        }
        plen = end0 - beg0;
        rlen = RSTRING_LEN(repl);
        len = RSTRING_LEN(str);
        if (rlen > plen) {
            RESIZE_CAPA(str, len + rlen - plen);
        }
        p = RSTRING_PTR(str);
        if (rlen != plen) {
            memmove(p + beg0 + rlen, p + beg0 + plen, len - beg0 - plen);
        }
        rp = RSTRING_PTR(repl);
        memmove(p + beg0, rp, rlen);
        len += rlen - plen;
        STR_SET_LEN(str, len);
        TERM_FILL(&RSTRING_PTR(str)[len], TERM_LEN(str));
        ENC_CODERANGE_SET(str, cr);

        RB_GC_GUARD(match);

        return str;
    }
    return Qnil;
}

#next ⇒ `String` #succ ⇒ `String`

Alias for #next.

#next! ⇒ `self` #succ! ⇒ `self`

Alias for #next!.

#sum(n = 16) ⇒ Integer

Returns a basic n-bit checksum of the characters in self; the checksum is the sum of the binary value of each byte in self, modulo 2**n - 1:

'hello'.sum     # => 532
'hello'.sum(4)  # => 4
'hello'.sum(64) # => 532
'тест'.sum      # => 1405
'こんにちは'.sum  # => 2582

This is not a particularly strong checksum.

Related: see Querying.

[ GitHub ]

# File 'string.c', line 10893


static VALUE
rb_str_sum(int argc, VALUE *argv, VALUE str)
{
    int bits = 16;
    char *ptr, *p, *pend;
    long len;
    VALUE sum = INT2FIX(0);
    unsigned long sum0 = 0;

    if (rb_check_arity(argc, 0, 1) && (bits = NUM2INT(argv[0])) < 0) {
        bits = 0;
    }
    ptr = p = RSTRING_PTR(str);
    len = RSTRING_LEN(str);
    pend = p + len;

    while (p < pend) {
        if (FIXNUM_MAX - UCHAR_MAX < sum0) {
            sum = rb_funcall(sum, '+', 1, LONG2FIX(sum0));
            str_mod_check(str, ptr, len);
            sum0 = 0;
        }
        sum0 += (unsigned char)*p;
        p++;
    }

    if (bits == 0) {
        if (sum0) {
            sum = rb_funcall(sum, '+', 1, LONG2FIX(sum0));
        }
    }
    else {
        if (sum == INT2FIX(0)) {
            if (bits < (int)sizeof(long)*CHAR_BIT) {
                sum0 &= (((unsigned long)1)<<bits)-1;
            }
            sum = LONG2FIX(sum0);
        }
        else {
            VALUE mod;

            if (sum0) {
                sum = rb_funcall(sum, '+', 1, LONG2FIX(sum0));
            }

            mod = rb_funcall(INT2FIX(1), idLTLT, 1, INT2FIX(bits));
            mod = rb_funcall(mod, '-', 1, INT2FIX(1));
            sum = rb_funcall(sum, '&', 1, mod);
        }
    }
    return sum;
}

#swapcase(mapping) ⇒ `String`

Returns a string containing the characters in self, with cases reversed:

Each uppercase character is downcased.
Each lowercase character is upcased.

Examples:

'Hello World!'.swapcase # => "hELLO wORLD!"
'тест'.swapcase         # => "ТЕСТ"

Some characters (and even character sets) do not have casing:

'12345'.swapcase    # => "12345"
'こんにちは'.swapcase # => "こんにちは"

The casing may be affected by the given mapping; see Case Mapping.

Related: see Converting to New String.

[ GitHub ]

# File 'string.c', line 8252


static VALUE
rb_str_swapcase(int argc, VALUE *argv, VALUE str)
{
    rb_encoding *enc;
    OnigCaseFoldType flags = ONIGENC_CASE_UPCASE | ONIGENC_CASE_DOWNCASE;
    VALUE ret;

    flags = check_case_options(argc, argv, flags);
    enc = str_true_enc(str);
    if (RSTRING_LEN(str) == 0 || !RSTRING_PTR(str)) return str_duplicate(rb_cString, str);
    if (flags&ONIGENC_CASE_ASCII_ONLY) {
        ret = rb_str_new(0, RSTRING_LEN(str));
        rb_str_ascii_casemap(str, ret, &flags, enc);
    }
    else {
        ret = rb_str_casemap(str, &flags, enc);
    }
    return ret;
}

#swapcase!(mapping) ⇒ `self`^?

Like #swapcase, except that:

Changes are made to self, not to copy of self.
Returns self if any changes are made, nil otherwise.

Related: see Modifying.

[ GitHub ]

# File 'string.c', line 8225


static VALUE
rb_str_swapcase_bang(int argc, VALUE *argv, VALUE str)
{
    rb_encoding *enc;
    OnigCaseFoldType flags = ONIGENC_CASE_UPCASE | ONIGENC_CASE_DOWNCASE;

    flags = check_case_options(argc, argv, flags);
    str_modify_keep_cr(str);
    enc = str_true_enc(str);
    if (flags&ONIGENC_CASE_ASCII_ONLY)
        rb_str_ascii_casemap(str, str, &flags, enc);
    else
        str_shared_replace(str, rb_str_casemap(str, &flags, enc));

    if (ONIGENC_CASE_MODIFIED&flags) return str;
    return Qnil;
}

#to_c ⇒ Complex

Returns a ::Complex object: parses the leading substring of self to extract two numeric values that become the coordinates of the complex object.

The substring is interpreted as containing either rectangular coordinates (real and imaginary parts) or polar coordinates (magnitude and angle parts), depending on an included or implied “separator” character:

'+', '-', or no separator: rectangular coordinates.
'@': polar coordinates.

In Brief

In these examples, we use method Complex#rect to display rectangular coordinates, and method Complex#polar to display polar coordinates.

# Rectangular coordinates.

# Real-only: no separator; imaginary part is zero.
'9'.to_c.rect         # => [9, 0]         # Integer.
'-9'.to_c.rect        # => [-9, 0]        # Integer (negative).
'2.5'.to_c.rect       # => [2.5, 0]       # Float.
'1.23e-14'.to_c.rect  # => [1.23e-14, 0]  # Float with exponent.
'2.5/1'.to_c.rect     # => [(5/2), 0]     # Rational.

# Some things are ignored.
'foo1'.to_c.rect      # => [0, 0]         # Unparsed entire substring.
'1foo'.to_c.rect      # => [1, 0]         # Unparsed trailing substring.
' 1 '.to_c.rect       # => [1, 0]         # Leading and trailing whitespace.
*
# Imaginary only: trailing 'i' required; real part is zero.
'9i'.to_c.rect        # => [0, 9]
'-9i'.to_c.rect       # => [0, -9]
'2.5i'.to_c.rect      # => [0, 2.5]
'1.23e-14i'.to_c.rect # => [0, 1.23e-14]
'2.5/1i'.to_c.rect    # => [0, (5/2)]

# Real and imaginary; '+' or '-' separator; trailing 'i' required.
'2+3i'.to_c.rect      # => [2, 3]
'-2-3i'.to_c.rect     # => [-2, -3]
'2.5+3i'.to_c.rect    # => [2.5, 3]
'2.5+3/2i'.to_c.rect  # => [2.5, (3/2)]

# Polar coordinates; '@' separator; magnitude required.
'1.0@0'.to_c.polar             # => [1.0, 0.0]
'1.0@'.to_c.polar              # => [1.0, 0.0]
"1.0@#{Math::PI}".to_c.polar   # => [1.0, 3.141592653589793]
"1.0@#{Math::PI/2}".to_c.polar # => [1.0, 1.5707963267948966]

Parsed Values

The parsing may be thought of as searching for numeric literals embedded in the substring.

This section shows how the method parses numeric values from leading substrings. The examples show real-only or imaginary-only parsing; the parsing is the same for each part.

'1foo'.to_c # => (1+0i)      # Ignores trailing unparsed characters.
' 1 '.to_c  # => (1+0i)      # Ignores leading and trailing whitespace.
'x1'.to_c   # => (0+0i)      # Finds no leading numeric.

# Integer literal embedded in the substring.
'1'.to_c       # => (1+0i)
'-1'.to_c      # => (-1+0i)
'1i'.to_c      # => (0+1i)

# Integer literals that don't work.
'0b100'.to_c   # => (0+0i)   # Not parsed as binary.
'0o100'.to_c   # => (0+0i)   # Not parsed as octal.
'0d100'.to_c   # => (0+0i)   # Not parsed as decimal.
'0x100'.to_c   # => (0+0i)   # Not parsed as hexadecimal.
'010'.to_c     # => (10+0i)  # Not parsed as octal.

# Float literals:
'3.14'.to_c    # => (3.14+0i)
'3.14i'.to_c   # => (0+3.14i)
'1.23e4'.to_c  # => (12300.0+0i)
'1.23e+4'.to_c # => (12300.0+0i)
'1.23e-4'.to_c # => (0.000123+0i)

# Rational literals:
'1/2'.to_c     # => ((1/2)+0i)
'-1/2'.to_c    # => ((-1/2)+0i)
'1/2r'.to_c    # => ((1/2)+0i)
'-1/2r'.to_c   # => ((-1/2)+0i)

Rectangular Coordinates

With separator '+' or '-', or with no separator, interprets the values as rectangular coordinates: real and imaginary.

With no separator, assigns a single value to either the real or the imaginary part:

 ''.to_c  # => (0+0i)  # Defaults to zero.
'1'.to_c  # => (1+0i)  # Real (no trailing 'i').
'1i'.to_c # => (0+1i)  # Imaginary (trailing 'i').
'i'.to_c  # => (0+1i)  # Special case (imaginary 1).

With separator '+', both parts positive (or zero):

# Without trailing 'i'.
'+'.to_c    # => (0+0i)  # No values: defaults to zero.
'+1'.to_c   # => (1+0i)  # Value after '+': real only.
'1+'.to_c   # => (1+0i)  # Value before '+': real only.
'2+1'.to_c  # => (2+0i)  # Values before and after '+': real and imaginary.
# With trailing 'i'.
'+1i'.to_c  # => (0+1i)  # Value after '+': imaginary only.
'2+i'.to_c  # => (2+1i)  # Value before '+': real and imaginary 1.
'2+1i'.to_c # => (2+1i)  # Values before and after '+': real and imaginary.

With separator '-', negative imaginary part:

# Without trailing 'i'.
'-'.to_c    # => (0+0i)   # No values: defaults to zero.
'-1'.to_c   # => (-1+0i)  # Value after '-': negative real, zero imaginary.
'1-'.to_c   # => (1+0i)   # Value before '-': positive real, zero imaginary.
'2-1'.to_c  # => (2+0i)   # Values before and after '-': positive real, zero imaginary.
# With trailing 'i'.
'-1i'.to_c  # => (0-1i)   # Value after '-': negative real, zero imaginary.
'2-i'.to_c  # => (2-1i)   # Value before '-': positive real, negative imaginary.
'2-1i'.to_c # => (2-1i)   # Values before and after '-': positive real, negative imaginary.

Note that the suffixed character 'i' may instead be one of 'I', 'j', or 'J', with the same effect.

Polar Coordinates

With separator '@') interprets the values as polar coordinates: magnitude and angle.

'2@'.to_c.polar  # => [2, 0.0]    # Value before '@': magnitude only.
 # Values before and after '@': magnitude and angle.
'2@1'.to_c.polar # => [2.0, 1.0]
"1.0@#{Math::PI/2}".to_c # => (0.0+1i)
"1.0@#{Math::PI}".to_c   # => (-1+0.0i)
# Magnitude not given: defaults to zero.
'@'.to_c.polar   # => [0, 0.0]
'@1'.to_c.polar  # => [0, 0.0]

'1.0@0'.to_c             # => (1+0.0i)

Note that in all cases, the suffixed character 'i' may instead be one of 'I', 'j', 'J', with the same effect.

See Converting to Non-String.

[ GitHub ]

# File 'complex.c', line 2383


static VALUE
string_to_c(VALUE self)
{
    VALUE num;

    rb_must_asciicompat(self);

    (void)parse_comp(rb_str_fill_terminator(self, 1), FALSE, &num);

    return num;
}

#to_f ⇒ Float

Returns the result of interpreting leading characters in self as a ::Float:

'3.14159'.to_f  # => 3.14159
'1.234e-2'.to_f # => 0.01234

Characters past a leading valid number are ignored:

'3.14 (pi to two places)'.to_f # => 3.14

Returns zero if there is no leading valid number:

'abcdef'.to_f # => 0.0

See Converting to Non-String.

[ GitHub ]

# File 'string.c', line 7091


static VALUE
rb_str_to_f(VALUE str)
{
    return DBL2NUM(rb_str_to_dbl(str, FALSE));
}

#to_i(base = 10) ⇒ Integer

Returns the result of interpreting leading characters in self as an integer in the given base; base must be either 0 or in range (2..36):

'123456'.to_i     # => 123456
'123def'.to_i(16) # => 1195503

With base zero given, string object may contain leading characters to specify the actual base:

'123def'.to_i(0)   # => 123
'0123def'.to_i(0)  # => 83
'0b123def'.to_i(0) # => 1
'0o123def'.to_i(0) # => 83
'0d123def'.to_i(0) # => 123
'0x123def'.to_i(0) # => 1195503

Characters past a leading valid number (in the given base) are ignored:

'12.345'.to_i   # => 12
'12345'.to_i(2) # => 1

Returns zero if there is no leading valid number:

'abcdef'.to_i # => 0
'2'.to_i(2)   # => 0

Related: see Converting to Non-String.

[ GitHub ]

# File 'string.c', line 7059


static VALUE
rb_str_to_i(int argc, VALUE *argv, VALUE str)
{
    int base = 10;

    if (rb_check_arity(argc, 0, 1) && (base = NUM2INT(argv[0])) < 0) {
        rb_raise(rb_eArgError, "invalid radix %d", base);
    }
    return rb_str_to_inum(str, base, FALSE);
}

#to_r ⇒ Rational

Returns the result of interpreting leading characters in self as a rational value:

'123'.to_r       # => (123/1)   # Integer literal.
'300/2'.to_r     # => (150/1)   # Rational literal.
'-9.2'.to_r      # => (-46/5)   # Float literal.
'-9.2e2'.to_r    # => (-920/1)  # Float literal.

Ignores leading and trailing whitespace, and trailing non-numeric characters:

' 2 '.to_r       # => (2/1)
'21-Jun-09'.to_r # => (21/1)

Returns Rational zero if there are no leading numeric characters.

'BWV 1079'.to_r  # => (0/1)

NOTE: '0.3'.to_r is equivalent to 3/10r, but is different from 0.3.to_r:

'0.3'.to_r # => (3/10)
3/10r      # => (3/10)
0.3.to_r   # => (5404319552844595/18014398509481984)

Related: see Converting to Non-String.

[ GitHub ]

# File 'rational.c', line 2497


static VALUE
string_to_r(VALUE self)
{
    VALUE num;

    rb_must_asciicompat(self);

    num = parse_rat(RSTRING_PTR(self), RSTRING_END(self), 0, TRUE);

    if (RB_FLOAT_TYPE_P(num) && !FLOAT_ZERO_P(num))
        rb_raise(rb_eFloatDomainError, "Infinity");
    return num;
}

#to_s ⇒ `self`, `String` Also known as: #to_str

Returns self if self is a String, or self converted to a String if self is a subclass of String.

[ GitHub ]

# File 'string.c', line 7106


static VALUE
rb_str_to_s(VALUE str)
{
    if (rb_obj_class(str) != rb_cString) {
        return str_duplicate(rb_cString, str);
    }
    return str;
}

#to_s ⇒ `self`, `String` #to_str ⇒ `self`, `String`

Alias for #to_s.

#intern ⇒ Symbol #to_sym ⇒ Symbol

Alias for #intern.

#tr(selector, replacements) ⇒ `String`

Returns a copy of self with each character specified by string selector translated to the corresponding character in string replacements. The correspondence is positional:

Each occurrence of the first character specified by selector is translated to the first character in replacements.
Each occurrence of the second character specified by selector is translated to the second character in replacements.
And so on.

Example:

'hello'.tr('el', 'ip') #=> "hippo"

If replacements is shorter than selector, it is implicitly padded with its own last character:

'hello'.tr('aeiou', '-')   # => "h-ll-"
'hello'.tr('aeiou', 'AA-') # => "hAll-"

Arguments selector and replacements must be valid character selectors (see Character Selectors), and may use any of its valid forms, including negation, ranges, and escaping:

# Negation.
'hello'.tr('^aeiou', '-') # => "-e--o"
# Ranges.
'ibm'.tr('b-z', 'a-z') # => "hal"
# Escapes.
'hel^lo'.tr('\^aeiou', '-')     # => "h-l-l-"    # Escaped leading caret.
'i-b-m'.tr('b\-z', 'a-z')       # => "ibabm"     # Escaped embedded hyphen.
'foo\\bar'.tr('ab\\', 'XYZ')    # => "fooZYXr"   # Escaped backslash.

[ GitHub ]

# File 'string.c', line 8655


static VALUE
rb_str_tr(VALUE str, VALUE src, VALUE repl)
{
    str = str_duplicate(rb_cString, str);
    tr_trans(str, src, repl, 0);
    return str;
}

#tr!(selector, replacements) ⇒ `self`^?

Like #tr, but modifies self in place. Returns self if any changes were made, nil otherwise.

[ GitHub ]

# File 'string.c', line 8609


static VALUE
rb_str_tr_bang(VALUE str, VALUE src, VALUE repl)
{
    return tr_trans(str, src, repl, 0);
}

#tr_s(selector, replacements) ⇒ `String`

Like #tr, but also squeezes the modified portions of the translated string; returns a new string (translated and squeezed).

'hello'.tr_s('l', 'r')   #=> "hero"
'hello'.tr_s('el', '-')  #=> "h-o"
'hello'.tr_s('el', 'hx') #=> "hhxo"

Related: #squeeze.

[ GitHub ]

# File 'string.c', line 8977


static VALUE
rb_str_tr_s(VALUE str, VALUE src, VALUE repl)
{
    str = str_duplicate(rb_cString, str);
    tr_trans(str, src, repl, 1);
    return str;
}

#tr_s!(selector, replacements) ⇒ `self`^?

Like #tr_s, but modifies self in place. Returns self if any changes were made, nil otherwise.

Related: #squeeze!.

[ GitHub ]

# File 'string.c', line 8955


static VALUE
rb_str_tr_s_bang(VALUE str, VALUE src, VALUE repl)
{
    return tr_trans(str, src, repl, 1);
}

#undump ⇒ `String`

Returns an unescaped version of self:

s_orig = "\f\x00\xff\\\""    # => "\f\u0000\xFF\\\""
s_dumped = s_orig.dump       # => "\"\\f\\x00\\xFF\\\\\\\"\""
s_undumped = s_dumped.undump # => "\f\u0000\xFF\\\""
s_undumped == s_orig         # => true

Related: #dump (inverse of undump).

[ GitHub ]

# File 'string.c', line 7642


static VALUE
str_undump(VALUE str)
{
    const char *s = RSTRING_PTR(str);
    const char *s_end = RSTRING_END(str);
    rb_encoding *enc = rb_enc_get(str);
    VALUE undumped = rb_enc_str_new(s, 0L, enc);
    bool utf8 = false;
    bool binary = false;
    int w;

    rb_must_asciicompat(str);
    if (rb_str_is_ascii_only_p(str) == Qfalse) {
        rb_raise(rb_eRuntimeError, "non-ASCII character detected");
    }
    if (!str_null_check(str, &w)) {
        rb_raise(rb_eRuntimeError, "string contains null byte");
    }
    if (RSTRING_LEN(str) < 2) goto invalid_format;
    if (*s != '"') goto invalid_format;

    /* strip '"' at the start */
    s++;

    for (;;) {
        if (s >= s_end) {
            rb_raise(rb_eRuntimeError, "unterminated dumped string");
        }

        if (*s == '"') {
            /* epilogue */
            s++;
            if (s == s_end) {
                /* ascii compatible dumped string */
                break;
            }
            else {
                static const char force_encoding_suffix[] = ".force_encoding(\""; /* "\")" */
                static const char dup_suffix[] = ".dup";
                const char *encname;
                int encidx;
                ptrdiff_t size;

                /* check separately for strings dumped by older versions */
                size = sizeof(dup_suffix) - 1;
                if (s_end - s > size && memcmp(s, dup_suffix, size) == 0) s += size;

                size = sizeof(force_encoding_suffix) - 1;
                if (s_end - s <= size) goto invalid_format;
                if (memcmp(s, force_encoding_suffix, size) != 0) goto invalid_format;
                s += size;

                if (utf8) {
                    rb_raise(rb_eRuntimeError, "dumped string contained Unicode escape but used force_encoding");
                }

                encname = s;
                s = memchr(s, '"', s_end-s);
                size = s - encname;
                if (!s) goto invalid_format;
                if (s_end - s != 2) goto invalid_format;
                if (s[0] != '"' || s[1] != ')') goto invalid_format;

                encidx = rb_enc_find_index2(encname, (long)size);
                if (encidx < 0) {
                    rb_raise(rb_eRuntimeError, "dumped string has unknown encoding name");
                }
                rb_enc_associate_index(undumped, encidx);
            }
            break;
        }

        if (*s == '\\') {
            s++;
            if (s >= s_end) {
                rb_raise(rb_eRuntimeError, "invalid escape");
            }
            undump_after_backslash(undumped, &s, s_end, &enc, &utf8, &binary);
        }
        else {
            rb_str_cat(undumped, s++, 1);
        }
    }

    RB_GC_GUARD(str);

    return undumped;
invalid_format:
    rb_raise(rb_eRuntimeError, "invalid dumped string; not wrapped with '\"' nor '\"...\".force_encoding(\"...\")' form");
}

#unicode_normalize(form = :nfc) ⇒ `String`

Returns a copy of self with Unicode normalization applied.

Argument form must be one of the following symbols (see Unicode normalization forms):

:nfc: Canonical decomposition, followed by canonical composition.
:nfd: Canonical decomposition.
:nfkc: Compatibility decomposition, followed by canonical composition.
:nfkd: Compatibility decomposition.

The encoding of self must be one of:

Encoding::UTF_8
Encoding::UTF_16BE
Encoding::UTF_16LE
Encoding::UTF_32BE
Encoding::UTF_32LE
Encoding::GB18030
Encoding::UCS_2BE
Encoding::UCS_4BE

Examples:

"a\u0300".unicode_normalize      # => "a"
"\u00E0".unicode_normalize(:nfd) # => "a "

[ GitHub ]

# File 'string.c', line 11954


static VALUE
rb_str_unicode_normalize(int argc, VALUE *argv, VALUE str)
{
    return unicode_normalize_common(argc, argv, str, id_normalize);
}

#unicode_normalize!(form = :nfc) ⇒ `self`

Like #unicode_normalize, except that the normalization is performed on self.

Related #unicode_normalized?.

[ GitHub ]

# File 'string.c', line 11970


static VALUE
rb_str_unicode_normalize_bang(int argc, VALUE *argv, VALUE str)
{
    return rb_str_replace(str, unicode_normalize_common(argc, argv, str, id_normalize));
}

#unicode_normalized?(form = :nfc) ⇒ `Boolean`

Returns true if self is in the given form of Unicode normalization, false otherwise. The form must be one of :nfc, :nfd, :nfkc, or :nfkd.

Examples:

"a\u0300".unicode_normalized?       # => false
"a\u0300".unicode_normalized?(:nfd) # => true
"\u00E0".unicode_normalized?        # => true
"\u00E0".unicode_normalized?(:nfd)  # => false

Raises an exception if self is not in a Unicode encoding:

s = "\xE0".force_encoding(Encoding::ISO_8859_1)
s.unicode_normalized? # Raises Encoding::CompatibilityError.

[ GitHub ]

# File 'string.c', line 11999


static VALUE
rb_str_unicode_normalized_p(int argc, VALUE *argv, VALUE str)
{
    return unicode_normalize_common(argc, argv, str, id_normalized_p);
}

#unpack(template, offset: 0, &block) ⇒ Array

Extracts data from self.

If block is not given, forming objects that become the elements of a new array, and returns that array. Otherwise, yields each object.

See Packed Data.

[ GitHub ]

# File 'pack.rb', line 23


def unpack(fmt, offset: 0)
  Primitive.attr! :use_block
  Primitive.pack_unpack(fmt, offset)
end

#unpack1(template, offset: 0) ⇒ Object

Like #unpack, but unpacks and returns only the first extracted object. See Packed Data.

[ GitHub ]

# File 'pack.rb', line 33


def unpack1(fmt, offset: 0)
  Primitive.pack_unpack1(fmt, offset)
end

#upcase(mapping) ⇒ `String`

Returns a string containing the upcased characters in self:

s = 'Hello World!' # => "Hello World!"
s.upcase           # => "HELLO WORLD!"

The casing may be affected by the given mapping; see Case Mapping.

Related: #upcase!, #downcase, #downcase!.

[ GitHub ]

# File 'string.c', line 8020


static VALUE
rb_str_upcase(int argc, VALUE *argv, VALUE str)
{
    rb_encoding *enc;
    OnigCaseFoldType flags = ONIGENC_CASE_UPCASE;
    VALUE ret;

    flags = check_case_options(argc, argv, flags);
    enc = str_true_enc(str);
    if (case_option_single_p(flags, enc, str)) {
        ret = rb_str_new(RSTRING_PTR(str), RSTRING_LEN(str));
        str_enc_copy_direct(ret, str);
        upcase_single(ret);
    }
    else if (flags&ONIGENC_CASE_ASCII_ONLY) {
        ret = rb_str_new(0, RSTRING_LEN(str));
        rb_str_ascii_casemap(str, ret, &flags, enc);
    }
    else {
        ret = rb_str_casemap(str, &flags, enc);
    }

    return ret;
}

#upcase!(mapping) ⇒ `self`^?

Upcases the characters in self; returns self if any changes were made, nil otherwise:

s = 'Hello World!' # => "Hello World!"
s.upcase!          # => "HELLO WORLD!"
s                  # => "HELLO WORLD!"
s.upcase!          # => nil

The casing may be affected by the given mapping; see Case Mapping.

Related: #upcase, #downcase, #downcase!.

[ GitHub ]

# File 'string.c', line 7981


static VALUE
rb_str_upcase_bang(int argc, VALUE *argv, VALUE str)
{
    rb_encoding *enc;
    OnigCaseFoldType flags = ONIGENC_CASE_UPCASE;

    flags = check_case_options(argc, argv, flags);
    str_modify_keep_cr(str);
    enc = str_true_enc(str);
    if (case_option_single_p(flags, enc, str)) {
        if (upcase_single(str))
            flags |= ONIGENC_CASE_MODIFIED;
    }
    else if (flags&ONIGENC_CASE_ASCII_ONLY)
        rb_str_ascii_casemap(str, str, &flags, enc);
    else
        str_shared_replace(str, rb_str_casemap(str, &flags, enc));

    if (ONIGENC_CASE_MODIFIED&flags) return str;
    return Qnil;
}

#upto(other_string, exclusive = false) {|string| ... } ⇒ `self` #upto(other_string, exclusive = false) ⇒ Enumerator

With a block given, calls the block with each String value returned by successive calls to String#succ; the first value is self, the next is self.succ, and so on; the sequence terminates when value other_string is reached; returns self:

'a8'.upto('b6') {|s| print s, ' ' } # => "a8"

Output:

a8 a9 b0 b1 b2 b3 b4 b5 b6

If argument exclusive is given as a truthy object, the last value is omitted:

'a8'.upto('b6', true) {|s| print s, ' ' } # => "a8"

Output:

a8 a9 b0 b1 b2 b3 b4 b5

If other_string would not be reached, does not call the block:

'25'.upto('5') {|s| fail s }
'aa'.upto('a') {|s| fail s }

With no block given, returns a new ::Enumerator:

'a8'.upto('b6') # => #<Enumerator: "a8":upto("b6")>

[ GitHub ]

# File 'string.c', line 5496


static VALUE
rb_str_upto(int argc, VALUE *argv, VALUE beg)
{
    VALUE end, exclusive;

    rb_scan_args(argc, argv, "11", &end, &exclusive);
    RETURN_ENUMERATOR(beg, argc, argv);
    return rb_str_upto_each(beg, end, RTEST(exclusive), str_upto_i, Qnil);
}

Class: String

Overview

Substitution Methods

Whitespace in Strings

What’s Here

Creating a String

Freezing/Unfreezing

Querying

Comparing

Modifying

Converting to New String

Converting to Non-String

Iterating

Class Method Summary

Instance Attribute Summary

Instance Method Summary

::Comparable - Included

Constructor Details

.new(*args)

#new(string = ''.encode(Encoding::ASCII_8BIT), **options) ⇒ String

Class Method Details

.try_convert(object) ⇒ Object, ...

Instance Attribute Details

#ascii_only? ⇒ Boolean (readonly)

#empty? ⇒ Boolean (readonly)

#valid_encoding? ⇒ Boolean (readonly)

Instance Method Details

#%(object) ⇒ String

#*(n) ⇒ String

#+(other_string) ⇒ String

#+ ⇒ String, self

#- ⇒ String Also known as: #dedup

#<<(object) ⇒ self

#<=>(other_string) ⇒ 1, ...

#==(object) ⇒ Boolean Also known as: #===

#==(object) ⇒ Boolean #===(object) ⇒ Boolean

#=~(object) ⇒ Integer?

#[](index) ⇒ String? #[](start, length) ⇒ String? #[](range) ⇒ String? #[](substring) ⇒ String? Also known as: #slice

#[]=(index, other_string) ⇒ String #[]=(start, length, other_string) ⇒ String #[]=(range, other_string) ⇒ String #[]=(substring, other_string) ⇒ String

#append_as_bytes(*objects) ⇒ self

#b ⇒ String

#byteindex(object, offset = 0) ⇒ Integer?

#byterindex(object, offset = self.bytesize) ⇒ Integer?

#bytes ⇒ array_of_bytes

#bytesize ⇒ Integer

#byteslice(offset, length = 1) ⇒ String? #byteslice(range) ⇒ String?

#bytesplice(offset, length, str) ⇒ self #bytesplice(offset, length, str, str_offset, str_length) ⇒ self #bytesplice(range, str) ⇒ self #bytesplice(range, str, str_range) ⇒ self

#capitalize(mapping = :ascii) ⇒ String

#capitalize!(mapping = :ascii) ⇒ self?

#casecmp(other_string) ⇒ 1, ...

#casecmp?(other_string) ⇒ true, ...

#center(size, pad_string = ' ') ⇒ String

#chars ⇒ array_of_characters

#chomp(line_sep = $/) ⇒ String

#chomp!(line_sep = $/) ⇒ self?

#chop ⇒ String

#chop! ⇒ self?

#chr ⇒ String

#clear ⇒ self

#codepoints ⇒ array_of_integers

#concat(*objects) ⇒ String

#count(*selectors) ⇒ Integer

#crypt(salt_str) ⇒ String

#- ⇒ String #dedup ⇒ String

#delete(*selectors) ⇒ String

#delete!(*selectors) ⇒ self?

#delete_prefix(prefix) ⇒ String

#delete_prefix!(prefix) ⇒ self?

#delete_suffix(suffix) ⇒ String

#delete_suffix!(suffix) ⇒ self?

#downcase(mapping) ⇒ String

#downcase!(mapping) ⇒ self?

#dump ⇒ String

#dup

#each_byte {|byte| ... } ⇒ self #each_byte ⇒ Enumerator

#each_char {|char| ... } ⇒ self #each_char ⇒ Enumerator

#each_codepoint {|codepoint| ... } ⇒ self #each_codepoint ⇒ Enumerator

#each_grapheme_cluster {|grapheme_cluster| ... } ⇒ self #each_grapheme_cluster ⇒ Enumerator

#each_line(record_separator = $/, chomp: false) {|substring| ... } ⇒ self #each_line(record_separator = $/, chomp: false) ⇒ Enumerator

#encode(dst_encoding = Encoding.default_internal, **enc_opts) ⇒ String #encode(dst_encoding, src_encoding, **enc_opts) ⇒ String

`::Comparable` - Included

#new(string = ''.encode(Encoding::ASCII_8BIT), **options) ⇒ `String`

#ascii_only? ⇒ `Boolean` (readonly)

#empty? ⇒ `Boolean` (readonly)

#valid_encoding? ⇒ `Boolean` (readonly)

#%(object) ⇒ `String`

#*(n) ⇒ `String`

#+(other_string) ⇒ `String`

#+ ⇒ `String`, `self`

#- ⇒ `String` Also known as: #dedup

#<<(object) ⇒ `self`

#<=>(other_string) ⇒ `1`, ...

#==(object) ⇒ `Boolean` Also known as: #===

#==(object) ⇒ `Boolean` #===(object) ⇒ `Boolean`

#=~(object) ⇒ Integer^?

#[](index) ⇒ `String`^? #[](start, length) ⇒ `String`^? #[](range) ⇒ `String`^? #[](substring) ⇒ `String`^?
Also known as: #slice

#[]=(index, other_string) ⇒ `String` #[]=(start, length, other_string) ⇒ `String` #[]=(range, other_string) ⇒ `String` #[]=(substring, other_string) ⇒ `String`

#append_as_bytes(*objects) ⇒ `self`

#b ⇒ `String`

#byteindex(object, offset = 0) ⇒ Integer^?

#byterindex(object, offset = self.bytesize) ⇒ Integer^?

#bytes ⇒ `array_of_bytes`

#byteslice(offset, length = 1) ⇒ `String`^? #byteslice(range) ⇒ `String`^?

#bytesplice(offset, length, str) ⇒ `self` #bytesplice(offset, length, str, str_offset, str_length) ⇒ `self` #bytesplice(range, str) ⇒ `self` #bytesplice(range, str, str_range) ⇒ `self`

#capitalize(mapping = :ascii) ⇒ `String`

#capitalize!(mapping = :ascii) ⇒ `self`^?

#casecmp(other_string) ⇒ `1`, ...

#casecmp?(other_string) ⇒ `true`, ...

#center(size, pad_string = ' ') ⇒ `String`

#chars ⇒ `array_of_characters`

#chomp(line_sep = $/) ⇒ `String`

#chomp!(line_sep = $/) ⇒ `self`^?

#chop ⇒ `String`

#chop! ⇒ `self`^?

#chr ⇒ `String`

#clear ⇒ `self`

#codepoints ⇒ `array_of_integers`

#concat(*objects) ⇒ `String`

#crypt(salt_str) ⇒ `String`

#- ⇒ `String` #dedup ⇒ `String`

#delete(*selectors) ⇒ `String`

#delete!(*selectors) ⇒ `self`^?

#delete_prefix(prefix) ⇒ `String`

#delete_prefix!(prefix) ⇒ `self`^?

#delete_suffix(suffix) ⇒ `String`

#delete_suffix!(suffix) ⇒ `self`^?

#downcase(mapping) ⇒ `String`

#downcase!(mapping) ⇒ `self`^?

#dump ⇒ `String`

#each_byte {|byte| ... } ⇒ `self` #each_byte ⇒ Enumerator

#each_char {|char| ... } ⇒ `self` #each_char ⇒ Enumerator

#each_codepoint {|codepoint| ... } ⇒ `self` #each_codepoint ⇒ Enumerator

#each_grapheme_cluster {|grapheme_cluster| ... } ⇒ `self` #each_grapheme_cluster ⇒ Enumerator

#each_line(record_separator = $/, chomp: false) {|substring| ... } ⇒ `self` #each_line(record_separator = $/, chomp: false) ⇒ Enumerator

#encode(dst_encoding = Encoding.default_internal, enc_opts) ⇒ `String` #encode(dst_encoding, src_encoding, enc_opts) ⇒ `String`

#encode!(dst_encoding = Encoding.default_internal, enc_opts) ⇒ `self` #encode!(dst_encoding, src_encoding, enc_opts) ⇒ `self`

#end_with?(*strings) ⇒ `Boolean`

#eql?(object) ⇒ `Boolean`

#force_encoding(encoding) ⇒ `self`

#getbyte(index) ⇒ Integer^?

#grapheme_clusters ⇒ `array_of_grapheme_clusters`

#gsub(pattern, replacement) ⇒ `String` #gsub(pattern) {|match| ... } ⇒ `String` #gsub(pattern) ⇒ Enumerator

#gsub!(pattern, replacement) ⇒ `self`^? #gsub!(pattern) {|match| ... } ⇒ `self`^? #gsub!(pattern) ⇒ Enumerator

#include?(other_string) ⇒ `Boolean`

#index(pattern, offset = 0) ⇒ Integer^?

#replace(other_string) ⇒ `self` #initialize_copy(other_string) ⇒ `self`

#insert(offset, other_string) ⇒ `self`

#inspect ⇒ `String`

#lines(record_separator = $/, chomp: false) ⇒ `String`

#ljust(width, pad_string = ' ') ⇒ `String`

#lstrip ⇒ `String`

#lstrip! ⇒ `self`^?

#match(pattern, offset = 0) ⇒ MatchData^? #match(pattern, offset = 0) {|matchdata| ... } ⇒ Object

#match?(pattern, offset = 0) ⇒ `Boolean`

#next ⇒ `String` Also known as: #succ

#next! ⇒ `self` Also known as: #succ!

#prepend(*other_strings) ⇒ `String`

#replace(other_string) ⇒ `self` Also known as: #initialize_copy

#reverse ⇒ `String`

#reverse! ⇒ `self`