class String
Overview
A String
represents an immutable sequence of UTF-8 characters.
A String
is typically created with a string literal, enclosing UTF-8 characters
in double quotes:
"hello world"
A backslash can be used to denote some characters inside the string:
"\"" # double quote
"\\" # backslash
"\e" # escape
"\f" # form feed
"\n" # newline
"\r" # carriage return
"\t" # tab
"\v" # vertical tab
You can use a backslash followed by an u and four hexadecimal characters to denote a unicode codepoint written:
"\u0041" # == "A"
Or you can use curly braces and specify up to six hexadecimal numbers (0 to 10FFFF):
"\u{41}" # == "A"
A string can span multiple lines:
"hello
world" # same as "hello\n world"
Note that in the above example trailing and leading spaces, as well as newlines, end up in the resulting string. To avoid this, you can split a string into multiple lines by joining multiple literals with a backslash:
"hello " \
"world, " \
"no newlines" # same as "hello world, no newlines"
Alternatively, a backslash followed by a newline can be inserted inside the string literal:
"hello \
world, \
no newlines" # same as "hello world, no newlines"
In this case, leading whitespace is not included in the resulting string.
If you need to write a string that has many double quotes, parentheses, or similar characters, you can use alternative literals:
# Supports double quotes and nested parentheses
%(hello ("world")) # same as "hello (\"world\")"
# Supports double quotes and nested brackets
%[hello ["world"]] # same as "hello [\"world\"]"
# Supports double quotes and nested curlies
%{hello {"world"}} # same as "hello {\"world\"}"
# Supports double quotes and nested angles
%<hello <"world">> # same as "hello <\"world\">"
To create a String
with embedded expressions, you can use string interpolation:
a = 1
b = 2
"sum = #{a + b}" # "sum = 3"
This ends up invoking Object#to_s(IO)
on each expression enclosed by #{...}
.
If you need to dynamically build a string, use String#build
or IO::Memory
.
Non UTF-8 valid strings
String might end up being conformed of bytes which are an invalid
byte sequence according to UTF-8. This can happen if the string is created
via one of the constructors that accept bytes, or when getting a string
from String.build
or IO::Memory
. No exception will be raised, but
invalid byte sequences, when asked as chars, will use the unicode replacement
char (value 0xFFFD). For example:
# here 255 is not a valid byte value in the UTF-8 encoding
string = String.new(Bytes[255, 97])
string.valid_encoding? # => false
# The first char here is the unicode replacement char
string.chars # => ['�', 'a']
One can also create strings with specific byte value in them by using octal and hexadecimal escape sequences:
# Octal escape sequences
"\101" # # => "A"
"\12" # # => "\n"
"\1" # string with one character with code point 1
"\377" # string with one byte with value 255
# Hexadecimal escape sequences
"\x45" # # => "A"
"\xFF" # string with one byte with value 255
The reason for allowing strings that don't have a valid UTF-8 sequence is that the world is full of content that isn't properly encoded, and having a program raise an exception or stop because of this is not good. It's better if programs are more resilient, but show a replacement character when there's an error in incoming data.
Included Modules
Defined in:
string.crbig/big_int.cr
big/big_float.cr
json/to_json.cr
yaml/to_yaml.cr
Constructors
-
.build(capacity = 64, &block) : self
Builds a
String
by creating aString::Builder
with the given initial capacity, yielding it to the block and finally getting aString
out of it. -
.new(bytes : Bytes, encoding : String, invalid : Symbol? = nil) : String
Creates a new
String
from the given bytes, which are encoded in the given encoding. -
.new(chars : Pointer(UInt8), bytesize, size = 0)
Creates a new
String
from a pointer, indicating its bytesize count and, optionally, the UTF-8 codepoints count (size). -
.new(slice : Bytes)
Creates a
String
from the given slice. -
.new(chars : Pointer(UInt8))
Creates a
String
from a pointer. - .new(capacity : Int, &block)
- .new(pull : JSON::PullParser)
- .new(pull : YAML::PullParser)
Instance Method Summary
-
#%(other)
Interpolates other into the string using
Kernel#sprintf
. -
#*(times : Int)
Makes a new
String
by adding str to itself times times. -
#+(other : self)
Concatenates str and other.
-
#+(char : Char)
Concatenates str and other.
-
#<=>(other : self)
Compares this string with other, returning
-1
,0
or+1
depending on whether this string is less, equal or greater than other. - #==(other : self)
-
#=~(other)
Tests whether str matches regex.
-
#=~(regex : Regex)
Tests whether str matches regex.
-
#[](start : Int, count : Int)
Returns a substring starting from the start character of size count.
- #[](regex : Regex, group)
-
#[](index : Int)
Returns the
Char
at the given index, or raisesIndexError
if out of bounds. -
#[](range : Range(Int, Int))
Returns a substring by using a Range's begin and end as character indices.
- #[](str : String | Char)
- #[](regex : Regex)
- #[]?(regex : Regex)
- #[]?(index : Int)
- #[]?(regex : Regex, group)
- #[]?(str : String | Char)
-
#ascii_only?
Returns
true
if this String is comprised in its entirety by ASCII characters. - #at(index : Int)
- #at(index : Int, &block)
-
#blank?
Returns
true
if this string consists exclusively of unicode whitespace. - #byte_at(index, &block)
- #byte_at(index)
- #byte_at?(index)
- #byte_index(string : String, offset = 0)
- #byte_index(byte : Int, offset = 0)
-
#byte_index_to_char_index(index)
Returns the char index of a byte index, or
nil
if out of bounds. - #byte_slice(start : Int, count : Int)
- #byte_slice(start : Int)
- #bytes
-
#bytesize : Int32
Returns the number of bytes in this string.
-
#camelcase
Converts underscores to camelcase boundaries.
-
#capitalize(options = Unicode::CaseOptions::None)
Returns a new
String
with the first letter converted to uppercase and every subsequent letter converted to lowercase. - #char_at(index)
-
#char_index_to_byte_index(index)
Returns the byte index of a char index, or
nil
if out of bounds. -
#chars
Returns an
Array
of all characters in the string. -
#check_no_null_byte
Raises an
ArgumentError
ifself
has null bytes. -
#chomp
Returns a new
String
with the last carriage return removed (that is, it will remove \n, \r, and \r\n). -
#chomp(suffix : String)
Returns a new
String
with suffix removed from the end of the string. -
#chomp(suffix : Char)
Returns a new
String
with suffix removed from the end of the string. - #clone
- #codepoint_at(index)
-
#codepoints
Returns an
Array
of the codepoints that make the string. -
#compare(other : String, case_insensitive = false)
Compares this string with other, returning
-1
,0
or+1
depending on whether this string is less, equal or greater than other, optionally in a case_insensitive manner. -
#count(&block)
Yields each char in this string to the block, returns the number of times the block returned a truthy value.
-
#count(other : Char)
Counts the occurrences of other char in this string.
-
#count(*sets)
Sets should be a list of strings following the rules described at
Char#in_set?
. -
#delete(&block)
Yields each char in this string to the block.
-
#delete(char : Char)
Returns a new
String
with all occurrences of char removed. -
#delete(*sets)
Sets should be a list of strings following the rules described at
Char#in_set?
. -
#downcase(options = Unicode::CaseOptions::None)
Returns a new
String
with each uppercase letter replaced with its lowercase counterpart. - #dump(io)
- #dump
- #dump_unquoted(io)
- #dump_unquoted
- #dup
-
#each_byte
Returns an
Iterator
over each byte in the string. -
#each_byte(&block)
Yields each byte in the string to the block.
-
#each_char
Returns an
Iterator
over each character in the string. -
#each_char(&block) : Nil
Yields each character in the string to the block.
-
#each_char_with_index(&block)
Yields each character and its index in the string to the block.
-
#each_codepoint(&block)
Yields each codepoint to the block.
-
#each_codepoint
Returns an
Iterator
for each codepoint. -
#each_line(chomp = true)
Returns an
Iterator
which yields each line of this string (seeString#each_line
). -
#each_line(chomp = true, &block) : Nil
Splits the string after each newline and yields each line to a block.
-
#empty?
Returns
true
if this is the empty string,""
. -
#encode(encoding : String, invalid : Symbol? = nil) : Bytes
Returns a slice of bytes containing this string encoded in the given encoding.
- #ends_with?(char : Char)
- #ends_with?(str : String)
-
#gsub(string : String, &block)
Returns a
String
where all occurrences of the given string are replaced with the block's value. -
#gsub(&block : Char -> _)
Returns a
String
where each character yielded to the given block is replaced by the block's return value. -
#gsub(char : Char, replacement)
Returns a
String
where all occurrences of the given char are replaced with the given replacement. -
#gsub(pattern : Regex, hash : Hash(String, _) | NamedTuple)
Returns a
String
where all occurrences of the given pattern are replaced with a hash of replacements. -
#gsub(pattern : Regex, replacement, backreferences = true)
Returns a
String
where all occurrences of the given pattern are replaced with the given replacement. -
#gsub(string : String, replacement)
Returns a
String
where all occurrences of the given string are replaced with the given replacement. -
#gsub(hash : Hash(Char, _))
Returns a
String
where all chars in the given hash are replaced by the corresponding hash values. -
#gsub(tuple : NamedTuple)
Returns a
String
where all chars in the given named tuple are replaced by the corresponding tuple values. -
#gsub(pattern : Regex, &block)
Returns a
String
where all occurrences of the given pattern are replaced by the block value's value. -
#has_back_references?
This returns
true
if this string has'\\'
in it. -
#hash
Returns a hash based on this string’s size and content.
-
#hexbytes : Bytes
Interprets this string as containing a sequence of hexadecimal values and decodes it as a slice of bytes.
-
#hexbytes? : Bytes?
Interprets this string as containing a sequence of hexadecimal values and decodes it as a slice of bytes.
-
#includes?(search : Char | String)
Returns
true
if the string contains search. -
#index(search : Regex, offset = 0)
Returns the index of search in the string, or
nil
if the string is not present. -
#index(search : String, offset = 0)
Returns the index of search in the string, or
nil
if the string is not present. -
#index(search : Char, offset = 0)
Returns the index of search in the string, or
nil
if the string is not present. -
#insert(index : Int, other : Char)
Returns a new
String
that results of inserting other inself
at index. -
#insert(index : Int, other : String)
Returns a new
String
that results of inserting other inself
at index. - #inspect(io)
- #inspect_unquoted
- #inspect_unquoted(io)
-
#lchop
Returns a new
String
with the first char removed from it. -
#lchop(prefix : String)
Returns a new
String
with prefix removed from the beginning of the string. -
#lchop(prefix : Char)
Returns a new
String
with prefix removed from the beginning of the string. - #lines(chomp = true)
-
#ljust(len, char : Char = ' ')
Adds instances of char to right of the string until it is at least size of len.
-
#lstrip(char : Char)
Returns a new string with leading occurrences of char removed.
-
#lstrip
Returns a new
String
with leading whitespace removed. -
#lstrip(&block : Char -> _)
Returns a new string where leading characters for which the block returns a truthy value are removed.
-
#lstrip(chars : String)
Returns a new string where leading occurrences of any char in chars are removed.
-
#match(regex : Regex, pos = 0) : Regex::MatchData?
Finds match of regex, starting at pos.
- #partition(search : Regex) : Tuple(String, String, String)
- #partition(search : Char | String) : Tuple(String, String, String)
- #pretty_print(pp)
-
#rchop
Returns a new
String
with the last character removed. -
#rchop(suffix : String)
Returns a new
String
with suffix removed from the end of the string. -
#rchop(suffix : Char)
Returns a new
String
with suffix removed from the end of the string. -
#reverse
Reverses the order of characters in the string.
-
#rindex(search : Char, offset = size - 1)
Returns the index of the last appearance of search in the string, If offset is present, it defines the position to end the search (characters beyond this point are ignored).
-
#rindex(search : String, offset = size - search.size)
Returns the index of the last appearance of search in the string, If offset is present, it defines the position to end the search (characters beyond this point are ignored).
-
#rindex(search : Regex, offset = 0)
Returns the index of the last appearance of search in the string, If offset is present, it defines the position to end the search (characters beyond this point are ignored).
-
#rjust(len, char : Char = ' ')
Adds instances of char to left of the string until it is at least size of len.
- #rpartition(search : Char | String) : Tuple(String, String, String)
- #rpartition(search : Regex) : Tuple(String, String, String)
-
#rstrip
Returns a new
String
with trailing whitespace removed. -
#rstrip(chars : String)
Returns a new string where trailing occurrences of any char in chars are removed.
-
#rstrip(char : Char)
Returns a new string with trailing occurrences of char removed.
-
#rstrip(&block : Char -> _)
Returns a new string where trailing characters for which the block returns a truthy value are removed.
-
#scan(pattern : String)
Searches the string for instances of pattern, returning an array of the matched string for each match.
-
#scan(pattern : Regex, &block)
Searches the string for instances of pattern, yielding a
Regex::MatchData
for each match. -
#scan(pattern : Regex)
Searches the string for instances of pattern, returning an
Array
ofRegex::MatchData
for each match. -
#scan(pattern : String, &block)
Searches the string for instances of pattern, yielding the matched string for each match.
-
#scrub(replacement = Char::REPLACEMENT) : String
Returns a String where bytes that are invalid in the UTF-8 encoding are replaced with replacement.
-
#size
Returns the number of unicode codepoints in this string.
-
#split(separator : Regex, limit = nil, &block : String -> _)
Makes an
Array
by splitting the string on separator (and removing instances of separator). -
#split(separator : Regex, limit = nil)
Splits the string after each regex separator and yields each part to a block.
-
#split(separator : String, limit = nil, &block : String -> _)
Splits the string after each string separator and yields each part to a block.
-
#split(limit : Int32? = nil)
Makes an array by splitting the string on any ASCII whitespace characters (and removing that whitespace).
-
#split(limit : Int32? = nil, &block : String -> _)
Splits the string after any ASCII whitespace character and yields each part to a block.
-
#split(separator : Char, limit = nil)
Makes an
Array
by splitting the string on the given character separator (and removing that character). -
#split(separator : String, limit = nil)
Makes an
Array
by splitting the string on separator (and removing instances of separator). -
#split(separator : Char, limit = nil, &block : String -> _)
Splits the string after each character separator and yields each part to a block.
-
#squeeze(&block)
Yields each char in this string to the block.
-
#squeeze(char : Char)
Returns a new
String
, with all runs of char replaced by one instance. -
#squeeze
Returns a new
String
, that has all characters removed, that were the same as the previous one. -
#squeeze(*sets : String)
Sets should be a list of strings following the rules described at
Char#in_set?
. - #starts_with?(char : Char)
- #starts_with?(str : String)
-
#strip(&block : Char -> _)
Returns a new string where leading and trailing characters for which the block returns a truthy value are removed.
-
#strip
Returns a new
String
with leading and trailing whitespace removed. -
#strip(chars : String)
Returns a new string where leading and trailing occurrences of any char in chars are removed.
-
#strip(char : Char)
Returns a new string where leading and trailing occurrences of char are removed.
-
#sub(pattern : Regex, &block)
Returns a
String
where the first occurrence of pattern is replaced by the block's return value. -
#sub(index : Int, replacement : Char)
Returns a new
String
with the character at the given index replaced by replacement. -
#sub(index : Int, replacement : String)
Returns a new
String
with the character at the given index replaced by replacement. -
#sub(range : Range(Int, Int), replacement : Char)
Returns a new
String
with characters at the given range replaced by replacement. -
#sub(range : Range(Int, Int), replacement : String)
Returns a new
String
with characters at the given range replaced by replacement. -
#sub(hash : Hash(Char, _))
Returns a
String
where the first char in the string matching a key in the given hash is replaced by the corresponding hash value. -
#sub(&block : Char -> _)
Returns a new
String
where the first character is yielded to the given block and replaced by its return value. -
#sub(char : Char, replacement)
Returns a
String
where the first occurrence of char is replaced by replacement. -
#sub(string : String, &block)
Returns a
String
where the first occurrences of the given string is replaced with the block's value. -
#sub(pattern : Regex, replacement, backreferences = true)
Returns a
String
where the first occurrence of pattern is replaced by replacement -
#sub(pattern : Regex, hash : Hash(String, _) | NamedTuple)
Returns a
String
where the first occurrences of the given pattern is replaced with the matching entry from the hash of replacements. -
#sub(string : String, replacement)
Returns a
String
where the first occurrences of the given string is replaced with the given replacement. -
#succ
Returns the successor of the string.
- #to_big_f
-
#to_big_i(base = 10) : BigInt
Returns a
BigInt
from this string, in the given base. -
#to_f(whitespace = true, strict = true)
Returns the result of interpreting characters in this string as a floating point number (
Float64
). -
#to_f32(whitespace = true, strict = true)
Same as
#to_f
but returns a Float32. -
#to_f32?(whitespace = true, strict = true)
Same as
#to_f?
but returns a Float32. -
#to_f64(whitespace = true, strict = true)
Same as
#to_f
. -
#to_f64?(whitespace = true, strict = true)
Same as
#to_f?
. -
#to_f?(whitespace = true, strict = true)
Returns the result of interpreting characters in this string as a floating point number (
Float64
). - #to_i(base : Int = 10, whitespace = true, underscore = false, prefix = false, strict = true, &block)
-
#to_i(base : Int = 10, whitespace = true, underscore = false, prefix = false, strict = true)
Returns the result of interpreting leading characters in this string as an integer base base (between 2 and 36).
- #to_i16(base : Int = 10, whitespace = true, underscore = false, prefix = false, strict = true, &block)
- #to_i16(base : Int = 10, whitespace = true, underscore = false, prefix = false, strict = true) : Int16
- #to_i16?(base : Int = 10, whitespace = true, underscore = false, prefix = false, strict = true) : Int16?
-
#to_i32(base : Int = 10, whitespace = true, underscore = false, prefix = false, strict = true) : Int32
Same as
#to_i
. -
#to_i32(base : Int = 10, whitespace = true, underscore = false, prefix = false, strict = true, &block)
Same as
#to_i
. -
#to_i32?(base : Int = 10, whitespace = true, underscore = false, prefix = false, strict = true) : Int32?
Same as
#to_i
. - #to_i64(base : Int = 10, whitespace = true, underscore = false, prefix = false, strict = true, &block)
- #to_i64(base : Int = 10, whitespace = true, underscore = false, prefix = false, strict = true) : Int64
- #to_i64?(base : Int = 10, whitespace = true, underscore = false, prefix = false, strict = true) : Int64?
- #to_i8(base : Int = 10, whitespace = true, underscore = false, prefix = false, strict = true) : Int8
- #to_i8(base : Int = 10, whitespace = true, underscore = false, prefix = false, strict = true, &block)
- #to_i8?(base : Int = 10, whitespace = true, underscore = false, prefix = false, strict = true) : Int8?
- #to_i?(base : Int = 10, whitespace = true, underscore = false, prefix = false, strict = true)
- #to_json(json : JSON::Builder)
- #to_s(io)
- #to_s
-
#to_slice : Bytes
Returns the underlying bytes of this String in an unsafe way.
- #to_u16(base : Int = 10, whitespace = true, underscore = false, prefix = false, strict = true) : UInt16
- #to_u16(base : Int = 10, whitespace = true, underscore = false, prefix = false, strict = true, &block)
- #to_u16?(base : Int = 10, whitespace = true, underscore = false, prefix = false, strict = true) : UInt16?
- #to_u32(base : Int = 10, whitespace = true, underscore = false, prefix = false, strict = true, &block)
- #to_u32(base : Int = 10, whitespace = true, underscore = false, prefix = false, strict = true) : UInt32
- #to_u32?(base : Int = 10, whitespace = true, underscore = false, prefix = false, strict = true) : UInt32?
- #to_u64(base : Int = 10, whitespace = true, underscore = false, prefix = false, strict = true, &block)
- #to_u64(base : Int = 10, whitespace = true, underscore = false, prefix = false, strict = true) : UInt64
- #to_u64?(base : Int = 10, whitespace = true, underscore = false, prefix = false, strict = true) : UInt64?
- #to_u8(base : Int = 10, whitespace = true, underscore = false, prefix = false, strict = true) : UInt8
- #to_u8(base : Int = 10, whitespace = true, underscore = false, prefix = false, strict = true, &block)
- #to_u8?(base : Int = 10, whitespace = true, underscore = false, prefix = false, strict = true) : UInt8?
-
#to_unsafe : Pointer(UInt8)
Returns a pointer to the underlying bytes of this String.
- #to_yaml(yaml : YAML::Builder)
-
#tr(from : String, to : String)
Returns a new string translating characters using from and to as a map.
-
#underscore
Converts camelcase boundaries to underscores.
- #unsafe_byte_at(index)
- #unsafe_byte_slice(byte_offset, count)
- #unsafe_byte_slice(byte_offset)
-
#upcase(options = Unicode::CaseOptions::None)
Returns a new
String
with each lowercase letter replaced with its uppercase counterpart. -
#valid_encoding?
Returns
true
if this String is encoded correctly according to the UTF-8 encoding.
Instance methods inherited from module Comparable(self)
<(other : T)
<,
<=(other : T)
<=,
<=>(other : T)
<=>,
==(other : T)
==,
>(other : T)
>,
>=(other : T)
>=
Instance methods inherited from class Reference
==(other : self)==(other) ==, dup dup, hash hash, inspect(io : IO) : Nil inspect, object_id : UInt64 object_id, pretty_print(pp) : Nil pretty_print, same?(other : Reference)
same?(other : Nil) same?, to_s(io : IO) : Nil to_s
Constructor methods inherited from class Reference
new
new
Instance methods inherited from class Object
!=(other)
!=,
!~(other)
!~,
==(other)
==,
===(other : JSON::Any)===(other : YAML::Any)
===(other) ===, =~(other) =~, class class, dup dup, hash hash, inspect(io : IO)
inspect inspect, itself itself, not_nil! not_nil!, pretty_inspect(width = 79, newline = "\n", indent = 0) : String pretty_inspect, pretty_print(pp : PrettyPrint) : Nil pretty_print, tap(&block) tap, to_json(io : IO)
to_json to_json, to_pretty_json(indent : String = " ")
to_pretty_json(io : IO, indent : String = " ") to_pretty_json, to_s
to_s(io : IO) to_s, to_yaml(io : IO)
to_yaml to_yaml, try(&block) try, unsafe_as(type : T.class) forall T unsafe_as
Constructor methods inherited from class Object
from_json(string_or_io, root : String) : selffrom_json(string_or_io) : self from_json, from_yaml(string_or_io) : self from_yaml
Constructor Detail
Builds a String
by creating a String::Builder
with the given initial capacity, yielding
it to the block and finally getting a String
out of it. The String::Builder
automatically
resizes as needed.
str = String.build do |str|
str << "hello "
str << 1
end
str # => "hello 1"
Creates a new String
from the given bytes, which are encoded in the given encoding.
The invalid argument can be:
nil
: an exception is raised on invalid byte sequences:skip
: invalid byte sequences are ignored
slice = Slice.new(2, 0_u8)
slice[0] = 186_u8
slice[1] = 195_u8
String.new(slice, "GB2312") # => "好"
Creates a new String
from a pointer, indicating its bytesize count
and, optionally, the UTF-8 codepoints count (size). Bytes
will be
copied from the pointer.
If the given size is zero, the amount of UTF-8 codepoints will be lazily computed when needed.
ptr = Pointer.malloc(4) { |i| ('a'.ord + i).to_u8 }
String.new(ptr, 2) # => "ab"
Creates a String
from the given slice. Bytes
will be copied from the slice.
This method is always safe to call, and the resulting string will have the contents and size of the slice.
slice = Slice.new(4) { |i| ('a'.ord + i).to_u8 }
String.new(slice) # => "abcd"
Creates a String
from a pointer. Bytes
will be copied from the pointer.
This method is unsafe: the pointer must point to data that eventually contains a zero byte that indicates the ends of the string. Otherwise, the result of this method is undefined and might cause a segmentation fault.
This method is typically used in C bindings, where you get a char*
from a
library and the library guarantees that this pointer eventually has an
ending zero byte.
ptr = Pointer.malloc(5) { |i| i == 4 ? 0_u8 : ('a'.ord + i).to_u8 }
String.new(ptr) # => "abcd"
Creates a new String
by allocating a buffer (Pointer(UInt8)
) with the given capacity, then
yielding that buffer. The block must return a tuple with the bytesize and size
(UTF-8 codepoints count) of the String. If the returned size is zero, the UTF-8 codepoints
count will be lazily computed.
The bytesize returned by the block must be less than or equal to the
capacity given to this String, otherwise ArgumentError
is raised.
If you need to build a String
where the maximum capacity is unknown, use String#build
.
str = String.new(4) do |buffer|
buffer[0] = 'a'.ord.to_u8
buffer[1] = 'b'.ord.to_u8
{2, 2}
end
str # => "ab"
Instance Method Detail
Interpolates other into the string using Kernel#sprintf
.
"Party like it's %d!!!" % 1999 # => "Party like it's 1999!!!"
Makes a new String
by adding str to itself times times.
"Developers! " * 4
# => "Developers! Developers! Developers! Developers!"
Concatenates str and other.
"abc" + "def" # => "abcdef"
"abc" + 'd' # => "abcd"
Concatenates str and other.
"abc" + "def" # => "abcdef"
"abc" + 'd' # => "abcd"
Compares this string with other, returning -1
, 0
or +1
depending on whether
this string is less, equal or greater than other.
Comparison is done byte-per-byte: if a byte is less then the other corresponding
byte, -1
is returned and so on.
If the strings are of different lengths, and the strings are equal when compared up to the shortest length, then the longer string is considered greater than the shorter one.
"abcdef" <=> "abcde" # => 1
"abcdef" <=> "abcdef" # => 0
"abcdef" <=> "abcdefg" # => -1
"abcdef" <=> "ABCDEF" # => 1
Tests whether str matches regex.
If successful, it returns the position of the first match.
If unsuccessful, it returns nil
.
If the argument isn't a Regex
, it returns nil
.
"Haystack" =~ /ay/ # => 1
"Haystack" =~ /z/ # => nil
"Haystack" =~ 45 # => nil
Tests whether str matches regex.
If successful, it returns the position of the first match.
If unsuccessful, it returns nil
.
If the argument isn't a Regex
, it returns nil
.
"Haystack" =~ /ay/ # => 1
"Haystack" =~ /z/ # => nil
"Haystack" =~ 45 # => nil
Returns a substring starting from the start character of size count.
The start argument can be negative to start counting from the end of the string.
Raises IndexError
if start isn't in range.
Raises ArgumentError
if count is negative.
Returns the Char
at the given index, or raises IndexError
if out of bounds.
Negative indices can be used to start counting from the end of the string.
"hello"[0] # 'h'
"hello"[1] # 'e'
"hello"[-1] # 'o'
"hello"[-2] # 'l'
"hello"[5] # raises IndexError
Returns a substring by using a Range's begin and end as character indices. Indices can be negative to start counting from the end of the string.
Raises IndexError
if the range's start is not in range.
"hello"[0..2] # "hel"
"hello"[0...2] # "he"
"hello"[1..-1] # "ello"
"hello"[1...-1] # "ell"
Returns true
if this String is comprised in its entirety
by ASCII characters.
"hello".ascii_only? # => true
"你好".ascii_only? # => false
Returns true
if this string consists exclusively of unicode whitespace.
"".blank? # => true
" ".blank? # => true
" a ".blank? # => false
Returns the char index of a byte index, or nil
if out of bounds.
It is valid to pass #bytesize
to index, and in this case the answer
will be the size of this string.
Returns this string's bytes as an Array(UInt8)
.
"hello".bytes # => [104, 101, 108, 108, 111]
"你好".bytes # => [228, 189, 160, 229, 165, 189]
Returns the number of bytes in this string.
"hello".bytesize # => 5
"你好".bytesize # => 6
Converts underscores to camelcase boundaries.
"eiffel_tower".camelcase # => "EiffelTower"
Returns a new String
with the first letter converted to uppercase and every
subsequent letter converted to lowercase.
"hEllO".capitalize # => "Hello"
Returns the byte index of a char index, or nil
if out of bounds.
It is valid to pass #size
to index, and in this case the answer
will be the bytesize of this string.
"hello".char_index_to_byte_index(1) # => 1
"hello".char_index_to_byte_index(5) # => 5
"こんにちは".char_index_to_byte_index(1) # => 3
"こんにちは".char_index_to_byte_index(5) # => 15
Raises an ArgumentError
if self
has null bytes. Returns self
otherwise.
This method should sometimes be called before passing a String
to a C function.
Returns a new String
with the last carriage return removed (that is, it
will remove \n, \r, and \r\n).
"string\r\n".chomp # => "string"
"string\n\r".chomp # => "string\n"
"string\n".chomp # => "string"
"string".chomp # => "string"
"x".chomp.chomp # => "x"
Returns a new String
with suffix removed from the end of the string.
If suffix is "\n"
then "\r\n"
is also removed if the string ends with it,
"hello".chomp("llo") # => "he"
"hello".chomp("ol") # => "hello"
Returns a new String
with suffix removed from the end of the string.
If suffix is '\n'
then "\r\n"
is also removed if the string ends with it,
"hello".chomp('o') # => "hell"
"hello".chomp('a') # => "hello"
Returns an Array
of the codepoints that make the string.
"ab☃".codepoints # => [97, 98, 9731]
See also: Char#ord
.
Compares this string with other, returning -1
, 0
or +1
depending on whether
this string is less, equal or greater than other, optionally in a case_insensitive
manner.
If case_insitive is false
, this method delegates to #<=>
. Otherwise,
the strings are compared char-by-char, and ASCII characters are compared in a
case-insensitive way.
"abcdef".compare("abcde") # => 1
"abcdef".compare("abcdef") # => 0
"abcdef".compare("abcdefg") # => -1
"abcdef".compare("ABCDEF") # => 1
"abcdef".compare("ABCDEF", case_insensitive: true) # => 0
"abcdef".compare("ABCDEG", case_insensitive: true) # => -1
Yields each char in this string to the block, returns the number of times the block returned a truthy value.
"aabbcc".count { |c| ['a', 'b'].includes?(c) } # => 4
Counts the occurrences of other char in this string.
"aabbcc".count('a') # => 2
Sets should be a list of strings following the rules
described at Char#in_set?
. Returns the number of characters
in this string that match the given set.
Yields each char in this string to the block.
Returns a new String
with all characters for which the
block returned a truthy value removed.
"aabbcc".delete { |c| ['a', 'b'].includes?(c) } # => "cc"
Returns a new String
with all occurrences of char removed.
"aabbcc".delete('b') # => "aacc"
Sets should be a list of strings following the rules
described at Char#in_set?
. Returns a new String
with
all characters that match the given set removed.
"aabbccdd".delete("a-c") # => "dd"
Returns a new String
with each uppercase letter replaced with its lowercase
counterpart.
"hEllO".downcase # => "hello"
Returns an Iterator
over each byte in the string.
bytes = "ab☃".each_byte
bytes.next # => 97
bytes.next # => 98
bytes.next # => 226
bytes.next # => 152
bytes.next # => 131
Yields each byte in the string to the block.
array = [] of UInt8
"ab☃".each_byte do |byte|
array << byte
end
array # => [97, 98, 226, 152, 131]
Returns an Iterator
over each character in the string.
chars = "ab☃".each_char
chars.next # => 'a'
chars.next # => 'b'
chars.next # => '☃'
Yields each character in the string to the block.
array = [] of Char
"ab☃".each_char do |char|
array << char
end
array # => ['a', 'b', '☃']
Yields each character and its index in the string to the block.
array = [] of Tuple(Char, Int32)
"ab☃".each_char_with_index do |char, index|
array << {char, index}
end
array # => [{'a', 0}, {'b', 1}, {'☃', 2}]
Yields each codepoint to the block.
array = [] of Int32
"ab☃".each_codepoint do |codepoint|
array << codepoint
end
array # => [97, 98, 9731]
See also: Char#ord
.
Returns an Iterator
for each codepoint.
codepoints = "ab☃".each_codepoint
codepoints.next # => 97
codepoints.next # => 98
codepoints.next # => 9731
See also: Char#ord
.
Returns an Iterator
which yields each line of this string (see String#each_line
).
Splits the string after each newline and yields each line to a block.
haiku = "the first cold shower
even the monkey seems to want
a little coat of straw"
haiku.each_line do |stanza|
puts stanza.upcase
end
# => THE FIRST COLD SHOWER
# => EVEN THE MONKEY SEEMS TO WANT
# => A LITTLE COAT OF STRAW
Returns a slice of bytes containing this string encoded in the given encoding.
The invalid argument can be:
nil
: an exception is raised on invalid byte sequences:skip
: invalid byte sequences are ignored
"好".encode("GB2312") # => Bytes[186, 195]
"好".bytes # => [229, 165, 189]
Returns a String
where all occurrences of the given string are replaced
with the block's value.
"hello yellow".gsub("ll") { "dd" } # => "heddo yeddow"
Returns a String
where each character yielded to the given block
is replaced by the block's return value.
"hello".gsub { |char| char + 1 } # => "ifmmp"
"hello".gsub { "hi" } # => "hihihihihi"
Returns a String
where all occurrences of the given char are
replaced with the given replacement.
"hello".gsub('l', "lo") # => "heloloo"
"hello world".gsub('o', 'a') # => "hella warld"
Returns a String
where all occurrences of the given pattern are replaced
with a hash of replacements. If the hash contains the matched pattern,
the corresponding value is used as a replacement. Otherwise the match is
not included in the returned string.
# "he" and "l" are matched and replaced,
# but "o" is not and so is not included
"hello".gsub(/(he|l|o)/, {"he": "ha", "l": "la"}) # => "halala"
Returns a String
where all occurrences of the given pattern are replaced
with the given replacement.
"hello".gsub(/[aeiou]/, '*') # => "h*ll*"
Within replacement, the special match variable $~
will not refer to the
current match.
If backreferences is true
(the default value), replacement can include backreferences:
"hello".gsub(/[aeiou]/, "(\\0)") # => "h(e)ll(o)"
When substitution is performed, any backreferences found in replacement
will be replaced with the contents of the corresponding capture group in
pattern. Backreferences to capture groups that were not present in
pattern or that did not match will be skipped. See Regex
for information
about capture groups.
Backreferences are expressed in the form "\\d"
, where d is a group
number, or "\\k
where name is the name of a named capture group.
A sequence of literal characters resembling a backreference can be
expressed by placing "\\"
before the sequence.
"foo".gsub(/o/, "x\\0x") # => "fxoxxox"
"foofoo".gsub(/(?<bar>oo)/, "|\\k<bar>|") # => "f|oo|f|oo|"
"foo".gsub(/o/, "\\\\0") # => "f\\0\\0"
Raises ArgumentError
if an incomplete named back-reference is present in
replacement.
Raises IndexError
if a named group referenced in replacement is not present
in pattern.
Returns a String
where all occurrences of the given string are replaced
with the given replacement.
"hello yellow".gsub("ll", "dd") # => "heddo yeddow"
Returns a String
where all chars in the given hash are replaced
by the corresponding hash values.
"hello".gsub({'e' => 'a', 'l' => 'd'}) # => "haddo"
Returns a String
where all chars in the given named tuple are replaced
by the corresponding tuple values.
"hello".gsub({e: 'a', l: 'd'}) # => "haddo"
Returns a String
where all occurrences of the given pattern are replaced
by the block value's value.
"hello".gsub(/./) { |s| s[0].ord.to_s + ' ' } # => "104 101 108 108 111 "
This returns true
if this string has '\\'
in it. It might not be a back reference,
but '\\'
is probably used for back references, so this check is faster than parsing
the whole thing.
Interprets this string as containing a sequence of hexadecimal values and decodes it as a slice of bytes. Two consecutive bytes in the string represent a byte in the returned slice.
Raises ArgumentError
if this string does not denote an hexstring.
"0102031aff".hexbytes # => Bytes[1, 2, 3, 26, 255]
"1".hexbytes # raises ArgumentError
"hello world".hexbytes # raises ArgumentError
Interprets this string as containing a sequence of hexadecimal values and decodes it as a slice of bytes. Two consecutive bytes in the string represent a byte in the returned slice.
Returns nil
if this string does not denote an hexstring.
"0102031aff".hexbytes? # => Bytes[1, 2, 3, 26, 255]
"1".hexbytes? # => nil
"hello world".hexbytes? # => nil
Returns true
if the string contains search.
"Team".includes?('i') # => false
"Dysfunctional".includes?("fun") # => true
Returns the index of search in the string, or nil
if the string is not present.
If offset is present, it defines the position to start the search.
"Hello, World".index('o') # => 4
"Hello, World".index('Z') # => nil
"Hello, World".index("o", 5) # => 8
"Hello, World".index("H", 2) # => nil
"Hello, World".index(/[ ]+/) # => 6
"Hello, World".index(/\d+/) # => nil
Returns the index of search in the string, or nil
if the string is not present.
If offset is present, it defines the position to start the search.
"Hello, World".index('o') # => 4
"Hello, World".index('Z') # => nil
"Hello, World".index("o", 5) # => 8
"Hello, World".index("H", 2) # => nil
"Hello, World".index(/[ ]+/) # => 6
"Hello, World".index(/\d+/) # => nil
Returns the index of search in the string, or nil
if the string is not present.
If offset is present, it defines the position to start the search.
"Hello, World".index('o') # => 4
"Hello, World".index('Z') # => nil
"Hello, World".index("o", 5) # => 8
"Hello, World".index("H", 2) # => nil
"Hello, World".index(/[ ]+/) # => 6
"Hello, World".index(/\d+/) # => nil
Returns a new String
that results of inserting other in self
at index.
Negative indices count from the end of the string, and insert after
the given index.
Raises IndexError
if the index is out of bounds.
"abcd".insert(0, 'X') # => "Xabcd"
"abcd".insert(3, 'X') # => "abcXd"
"abcd".insert(4, 'X') # => "abcdX"
"abcd".insert(-3, 'X') # => "abXcd"
"abcd".insert(-1, 'X') # => "abcdX"
"abcd".insert(5, 'X') # raises IndexError
"abcd".insert(-6, 'X') # raises IndexError
Returns a new String
that results of inserting other in self
at index.
Negative indices count from the end of the string, and insert after
the given index.
Raises IndexError
if the index is out of bounds.
"abcd".insert(0, "FOO") # => "FOOabcd"
"abcd".insert(3, "FOO") # => "abcFOOd"
"abcd".insert(4, "FOO") # => "abcdFOO"
"abcd".insert(-3, "FOO") # => "abFOOcd"
"abcd".insert(-1, "FOO") # => "abcdFOO"
"abcd".insert(5, "FOO") # raises IndexError
"abcd".insert(-6, "FOO") # raises IndexError
Returns a new String
with the first char removed from it.
Applying lchop to an empty string returns an empty string.
"hello".lchop # => "ello"
"".lchop # => ""
Returns a new String
with prefix removed from the beginning of the string.
"hello".lchop("hel") # => "lo"
"hello".lchop("eh") # => "hello"
Returns a new String
with prefix removed from the beginning of the string.
"hello".lchop('h') # => "ello"
"hello".lchop('g') # => "hello"
Adds instances of char to right of the string until it is at least size of len.
"Purple".ljust(8) # => "Purple "
"Purple".ljust(8, '-') # => "Purple--"
"Aubergine".ljust(8) # => "Aubergine"
Returns a new string with leading occurrences of char removed.
"aaabcdaaa".lstrip('a') # => "bcdaaa"
Returns a new String
with leading whitespace removed.
" hello ".lstrip # => "hello "
"\tgoodbye\r\n".lstrip # => "goodbye\r\n"
Returns a new string where leading characters for which the block returns a truthy value are removed.
"bcadefcba".lstrip { |c| 'a' <= c <= 'c' } # => "defcba"
Returns a new string where leading occurrences of any char in chars are removed. The chars argument is not a suffix; rather; all combinations of its values are stripped.
"bcadefcba".lstrip("abc") # => "defcba"
Finds match of regex, starting at pos.
Searches separator or pattern (Regex
) in the string, and returns
a Tuple
with the part before it, the match, and the part after it.
If it is not found, returns str followed by two empty strings.
"hello".partition("l") # => {"he", "l", "lo"}
"hello".partition("x") # => {"hello", "", ""}
Searches separator or pattern (Regex
) in the string, and returns
a Tuple
with the part before it, the match, and the part after it.
If it is not found, returns str followed by two empty strings.
"hello".partition("l") # => {"he", "l", "lo"}
"hello".partition("x") # => {"hello", "", ""}
Returns a new String
with the last character removed.
Applying rchop to an empty string returns an empty string.
"string\r\n".rchop # => "string\r"
"string\n\r".rchop # => "string\n"
"string\n".rchop # => "string"
"string".rchop # => "strin"
"x".rchop.rchop # => ""
Returns a new String
with suffix removed from the end of the string.
"string".rchop("ing") # => "str"
"string".rchop("inx") # => "string"
Returns a new String
with suffix removed from the end of the string.
"string".rchop('g') # => "strin"
"string".rchop('x') # => "string"
Reverses the order of characters in the string.
"Argentina".reverse # => "anitnegrA"
"racecar".reverse # => "racecar"
Returns the index of the last appearance of search in the string, If offset is present, it defines the position to end the search (characters beyond this point are ignored).
"Hello, World".rindex('o') # => 8
"Hello, World".rindex('Z') # => nil
"Hello, World".rindex("o", 5) # => 4
"Hello, World".rindex("W", 2) # => nil
Returns the index of the last appearance of search in the string, If offset is present, it defines the position to end the search (characters beyond this point are ignored).
"Hello, World".rindex('o') # => 8
"Hello, World".rindex('Z') # => nil
"Hello, World".rindex("o", 5) # => 4
"Hello, World".rindex("W", 2) # => nil
Returns the index of the last appearance of search in the string, If offset is present, it defines the position to end the search (characters beyond this point are ignored).
"Hello, World".rindex('o') # => 8
"Hello, World".rindex('Z') # => nil
"Hello, World".rindex("o", 5) # => 4
"Hello, World".rindex("W", 2) # => nil
Adds instances of char to left of the string until it is at least size of len.
"Purple".rjust(8) # => " Purple"
"Purple".rjust(8, '-') # => "--Purple"
"Aubergine".rjust(8) # => "Aubergine"
Searches separator or pattern (Regex
) in the string from the end of the string,
and returns a Tuple
with the part before it, the match, and the part after it.
If it is not found, returns two empty strings and str.
"hello".rpartition("l") # => {"hel", "l", "o"}
"hello".rpartition("x") # => {"", "", "hello"}
"hello".rpartition(/.l/) # => {"he", "ll", "o"}
Searches separator or pattern (Regex
) in the string from the end of the string,
and returns a Tuple
with the part before it, the match, and the part after it.
If it is not found, returns two empty strings and str.
"hello".rpartition("l") # => {"hel", "l", "o"}
"hello".rpartition("x") # => {"", "", "hello"}
"hello".rpartition(/.l/) # => {"he", "ll", "o"}
Returns a new String
with trailing whitespace removed.
" hello ".rstrip # => " hello"
"\tgoodbye\r\n".rstrip # => "\tgoodbye"
Returns a new string where trailing occurrences of any char in chars are removed. The chars argument is not a suffix; rather; all combinations of its values are stripped.
"abcdefcba".rstrip("abc") # => "abcdef"
Returns a new string with trailing occurrences of char removed.
"aaabcdaaa".rstrip('a') # => "aaabcd"
Returns a new string where trailing characters for which the block returns a truthy value are removed.
"bcadefcba".rstrip { |c| 'a' <= c <= 'c' } # => "bcadef"
Searches the string for instances of pattern, returning an array of the matched string for each match.
Searches the string for instances of pattern,
yielding a Regex::MatchData
for each match.
Searches the string for instances of pattern,
returning an Array
of Regex::MatchData
for each match.
Searches the string for instances of pattern, yielding the matched string for each match.
Returns a String where bytes that are invalid in the UTF-8 encoding are replaced with replacement.
Returns the number of unicode codepoints in this string.
"hello".size # => 5
"你好".size # => 2
Makes an Array
by splitting the string on separator (and removing instances of separator).
If limit is present, the array will be limited to limit items and the final item will contain the remainder of the string.
If separator is an empty regex (//
), the string will be separated into one-character strings.
long_river_name = "Mississippi"
long_river_name.split(/s+/) # => ["Mi", "i", "ippi"]
long_river_name.split(//) # => ["M", "i", "s", "s", "i", "s", "s", "i", "p", "p", "i"]
Splits the string after each regex separator and yields each part to a block.
If limit is present, the array will be limited to limit items and the final item will contain the remainder of the string.
If separator is an empty regex (//
), the string will be separated into one-character strings.
ary = [] of String
long_river_name = "Mississippi"
long_river_name.split(/s+/) { |s| ary << s }
ary # => ["Mi", "i", "ippi"]
ary.clear
long_river_name.split(//) { |s| ary << s }
ary # => ["M", "i", "s", "s", "i", "s", "s", "i", "p", "p", "i"]
Splits the string after each string separator and yields each part to a block.
If limit is present, the array will be limited to limit items and the final item will contain the remainder of the string.
If separator is an empty string (""
), the string will be separated into one-character strings.
ary = [] of String
long_river_name = "Mississippi"
long_river_name.split("ss") { |s| ary << s }
ary # => ["Mi", "i", "ippi"]
ary.clear
long_river_name.split("i") { |s| ary << s }
ary # => ["M", "ss", "ss", "pp", ""]
ary.clear
long_river_name.split("") { |s| ary << s }
ary # => ["M", "i", "s", "s", "i", "s", "s", "i", "p", "p", "i"]
Makes an array by splitting the string on any ASCII whitespace characters (and removing that whitespace).
If limit is present, up to limit new strings will be created, with the entire remainder added to the last string.
old_pond = "
Old pond
a frog leaps in
water's sound
"
old_pond.split # => ["Old", "pond", "a", "frog", "leaps", "in", "water's", "sound"]
old_pond.split(3) # => ["Old", "pond", "a frog leaps in\n water's sound\n"]
Splits the string after any ASCII whitespace character and yields each part to a block.
If limit is present, up to limit new strings will be created, with the entire remainder added to the last string.
ary = [] of String
old_pond = "
Old pond
a frog leaps in
water's sound
"
old_pond.split { |s| ary << s }
ary # => ["Old", "pond", "a", "frog", "leaps", "in", "water's", "sound"]
ary.clear
old_pond.split(3) { |s| ary << s }
ary # => ["Old", "pond", "a frog leaps in\n water's sound\n"]
Makes an Array
by splitting the string on the given character separator
(and removing that character).
If limit is present, up to limit new strings will be created, with the entire remainder added to the last string.
"foo,bar,baz".split(',') # => ["foo", "bar", "baz"]
"foo,bar,baz".split(',', 2) # => ["foo", "bar,baz"]
Makes an Array
by splitting the string on separator (and removing instances of separator).
If limit is present, the array will be limited to limit items and the final item will contain the remainder of the string.
If separator is an empty string (""
), the string will be separated into one-character strings.
long_river_name = "Mississippi"
long_river_name.split("ss") # => ["Mi", "i", "ippi"]
long_river_name.split("i") # => ["M", "ss", "ss", "pp", ""]
long_river_name.split("") # => ["M", "i", "s", "s", "i", "s", "s", "i", "p", "p", "i"]
Splits the string after each character separator and yields each part to a block.
If limit is present, up to limit new strings will be created, with the entire remainder added to the last string.
ary = [] of String
"foo,bar,baz".split(',') { |string| ary << string }
ary # => ["foo", "bar", "baz"]
ary.clear
"foo,bar,baz".split(',', 2) { |string| ary << string }
ary # => ["foo", "bar,baz"]
Yields each char in this string to the block.
Returns a new String
, that has all characters removed,
that were the same as the previous one and for which the given
block returned a truthy value.
"aaabbbccc".squeeze { |c| ['a', 'b'].includes?(c) } # => "abccc"
"aaabbbccc".squeeze { |c| ['a', 'c'].includes?(c) } # => "abbbc"
Returns a new String
, with all runs of char replaced by one instance.
"a bbb".squeeze(' ') # => "a bbb"
Returns a new String
, that has all characters removed,
that were the same as the previous one.
"a bbb".squeeze # => "a b"
Sets should be a list of strings following the rules
described at Char#in_set?
. Returns a new String
with all
runs of the same character replaced by one instance, if
they match the given set.
If no set is given, all characters are matched.
"aaabbbcccddd".squeeze("b-d") # => "aaabcd"
"a bbb".squeeze # => "a b"
Returns a new string where leading and trailing characters for which the block returns a truthy value are removed.
"bcadefcba".strip { |c| 'a' <= c <= 'c' } # => "def"
Returns a new String
with leading and trailing whitespace removed.
" hello ".strip # => "hello"
"\tgoodbye\r\n".strip # => "goodbye"
Returns a new string where leading and trailing occurrences of any char in chars are removed. The chars argument is not a prefix or suffix; rather; all combinations of its values are stripped.
"abcdefcba".strip("abc") # => "def"
Returns a new string where leading and trailing occurrences of char are removed.
"aaabcdaaa".strip('a') # => "bcd"
Returns a String
where the first occurrence of pattern is replaced by
the block's return value.
"hello".sub(/./) { |s| s[0].ord.to_s + ' ' } # => "104 ello"
Returns a new String
with the character at the given index
replaced by replacement.
"hello".sub(1, 'a') # => "hallo"
Returns a new String
with the character at the given index
replaced by replacement.
"hello".sub(1, "eee") # => "heeello"
Returns a new String
with characters at the given range
replaced by replacement.
"hello".sub(1..2, 'a') # => "halo"
Returns a new String
with characters at the given range
replaced by replacement.
"hello".sub(1..2, "eee") # => "heeelo"
Returns a String
where the first char in the string matching a key in the
given hash is replaced by the corresponding hash value.
"hello".sub({'a' => 'b', 'l' => 'd'}) # => "hedlo"
Returns a new String
where the first character is yielded to the given
block and replaced by its return value.
"hello".sub { |char| char + 1 } # => "iello"
"hello".sub { "hi" } # => "hiello"
Returns a String
where the first occurrence of char is replaced by
replacement.
"hello".sub('l', "lo") # => "helolo"
"hello world".sub('o', 'a') # => "hella world"
Returns a String
where the first occurrences of the given string is replaced
with the block's value.
"hello yellow".sub("ll") { "dd" } # => "heddo yellow"
Returns a String
where the first occurrence of pattern is replaced by
replacement
"hello".sub(/[aeiou]/, "*") # => "h*llo"
Within replacement, the special match variable $~
will not refer to the
current match.
If backreferences is true
(the default value), replacement can include backreferences:
"hello".sub(/[aeiou]/, "(\\0)") # => "h(e)llo"
When substitution is performed, any backreferences found in replacement
will be replaced with the contents of the corresponding capture group in
pattern. Backreferences to capture groups that were not present in
pattern or that did not match will be skipped. See Regex
for information
about capture groups.
Backreferences are expressed in the form "\\d"
, where d is a group
number, or "\\k<name>"
where name is the name of a named capture group.
A sequence of literal characters resembling a backreference can be
expressed by placing "\\"
before the sequence.
"foo".sub(/o/, "x\\0x") # => "fxoxo"
"foofoo".sub(/(?<bar>oo)/, "|\\k<bar>|") # => "f|oo|foo"
"foo".sub(/o/, "\\\\0") # => "f\\0o"
Raises ArgumentError
if an incomplete named back-reference is present in
replacement.
Raises IndexError
if a named group referenced in replacement is not present
in pattern.
Returns a String
where the first occurrences of the given pattern is replaced
with the matching entry from the hash of replacements. If the first match
is not included in the hash, nothing is replaced.
"hello".sub(/(he|l|o)/, {"he": "ha", "l": "la"}) # => "hallo"
"hello".sub(/(he|l|o)/, {"l": "la"}) # => "hello"
Returns a String
where the first occurrences of the given string is replaced
with the given replacement.
"hello yellow".sub("ll", "dd") # => "heddo yellow"
Returns the successor of the string. The successor is calculated by incrementing characters starting from the rightmost alphanumeric (or the rightmost character if there are no alphanumerics) in the string. Incrementing a digit always results in another digit, and incrementing a letter results in another letter of the same case.
If the increment generates a "carry", the character to the left of it is incremented. This process repeats until there is no carry, adding an additional character if necessary.
"abcd".succ # => "abce"
"THX1138".succ # => "THX1139"
"((koala))".succ # => "((koalb))"
"1999zzz".succ # => "2000aaa"
"ZZZ9999".succ # => "AAAA0000"
"***".succ # => "**+"
Returns a BigInt
from this string, in the given base.
Raises ArgumentError
if this string doesn't denote a valid integer.
Returns the result of interpreting characters in this string as a floating point number (Float64
).
This method raises an exception if the string is not a valid float representation.
Options:
- whitespace: if
true
, leading and trailing whitespaces are allowed - strict: if
true
, extraneous characters past the end of the number are disallowed
"123.45e1".to_f # => 1234.5
"45.67 degrees".to_f # raises ArgumentError
"thx1138".to_f(strict: false) # raises ArgumentError
" 1.2".to_f(whitespace: false) # raises ArgumentError
"1.2foo".to_f(strict: false) # => 1.2
Returns the result of interpreting characters in this string as a floating point number (Float64
).
This method returns nil
if the string is not a valid float representation.
Options:
- whitespace: if
true
, leading and trailing whitespaces are allowed - strict: if
true
, extraneous characters past the end of the number are disallowed
"123.45e1".to_f? # => 1234.5
"45.67 degrees".to_f? # => nil
"thx1138".to_f? # => nil
" 1.2".to_f?(whitespace: false) # => nil
"1.2foo".to_f?(strict: false) # => 1.2
Same as #to_i
, but returns the block's value if there is not a valid number at the start
of this string, or if the resulting integer doesn't fit an Int32
.
"12345".to_i { 0 } # => 12345
"hello".to_i { 0 } # => 0
Returns the result of interpreting leading characters in this string as an integer base base (between 2 and 36).
If there is not a valid number at the start of this string,
or if the resulting integer doesn't fit an Int32
, an ArgumentError
is raised.
Options:
- whitespace: if
true
, leading and trailing whitespaces are allowed - underscore: if
true
, underscores in numbers are allowed - prefix: if
true
, the prefixes"0x"
,"0"
and"0b"
override the base - strict: if
true
, extraneous characters past the end of the number are disallowed
"12345".to_i # => 12345
"0a".to_i # raises ArgumentError
"hello".to_i # raises ArgumentError
"0a".to_i(16) # => 10
"1100101".to_i(2) # => 101
"1100101".to_i(8) # => 294977
"1100101".to_i(10) # => 1100101
"1100101".to_i(base: 16) # => 17826049
"12_345".to_i # raises ArgumentError
"12_345".to_i(underscore: true) # => 12345
" 12345 ".to_i # => 12345
" 12345 ".to_i(whitespace: false) # raises ArgumentError
"0x123abc".to_i # raises ArgumentError
"0x123abc".to_i(prefix: true) # => 1194684
"99 red balloons".to_i # raises ArgumentError
"99 red balloons".to_i(strict: false) # => 99
Same as #to_i
.
Same as #to_i
.
Same as #to_i
.
Same as #to_i
, but returns nil
if there is not a valid number at the start
of this string, or if the resulting integer doesn't fit an Int32
.
"12345".to_i? # => 12345
"99 red balloons".to_i? # => nil
"0a".to_i?(strict: false) # => 0
"hello".to_i? # => nil
Returns the underlying bytes of this String in an unsafe way.
The returned slice is read-only.
Returns a pointer to the underlying bytes of this String.
Returns a new string translating characters using from and to as a
map. If to is shorter than from, the last character in to is used for
the rest. If to is empty, this acts like String#delete
.
"aabbcc".tr("abc", "xyz") # => "xxyyzz"
"aabbcc".tr("abc", "x") # => "xxxxxx"
"aabbcc".tr("a", "xyz") # => "xxbbcc"
Converts camelcase boundaries to underscores.
"DoesWhatItSaysOnTheTin".underscore # => "does_what_it_says_on_the_tin"
"PartyInTheUSA".underscore # => "party_in_the_usa"
"HTTP_CLIENT".underscore # => "http_client"
"3.14IsPi".underscore # => "3.14_is_pi"
Returns a new String
with each lowercase letter replaced with its uppercase
counterpart.
"hEllO".upcase # => "HELLO"
Returns true
if this String is encoded correctly
according to the UTF-8 encoding.