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
.
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 "\x41" # # => "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.
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.
Decodes the given slice UTF-16 sequence into a String.
Creates a String
from the given slice.
Creates a String
from a pointer.
Creates a new String
from a pointer, indicating its bytesize count and, optionally, the UTF-8 codepoints count (size).
Creates a new String
from the given bytes, which are encoded in the given encoding.
Decodes the given slice UTF-16 sequence into a String and returns the pointer after reading.
Implementation of string interpolation of multiple, possibly non-string values.
Implementation of string interpolation of multiple string values.
Implementation of string interpolation of a single non-string value.
Implementation of string interpolation of a single string.
Implementation of string interpolation of a char and a string.
Implementation of string interpolation of a string and a char.
Interpolates other into the string using Kernel#sprintf
.
Makes a new String
by adding str to itself times times.
Concatenates str and other.
Concatenates str and other.
The comparison operator.
Returns true
if this string is equal to `other.
Tests whether str matches regex.
Tests whether str matches regex.
Returns a substring starting from the start character of size count.
Returns a substring by using a Range's begin and end as character indices.
Returns the Char
at the given index.
Like #[Int, Int]
but returns nil
if the start index is out of bounds.
Like #[Range]
, but returns nil
if the range's start is out of bounds.
Returns true
if this String is comprised in its entirety by ASCII characters.
Returns true
if this string consists exclusively of unicode whitespace.
Returns the byte at the given index.
Returns the byte at the given index, or yields if out of bounds.
Returns the byte at the given index, or nil
if out of bounds.
Returns the index of the first ocurrence of byte in the string, or nil
if not present.
Returns the byte index of search in the string, or nil
if the string is not present.
Returns the char index of a byte index, or nil
if out of bounds.
Returns a new string built from count bytes starting at start byte.
Returns a substring starting from the start byte.
Like #byte_slice(Int, Int)
but returns Nil
if the start index is out of bounds.
Returns the number of bytes in this string.
Writes an camelcased version of self
to the given io.
Converts underscores to camelcase boundaries.
Writes a capitalized version of self
to the given io.
Returns a new String
with the first letter converted to uppercase and every subsequent letter converted to lowercase.
Adds instances of char to left and right of the string until it is at least size of len, then appends the result to the given IO.
Adds spaces to left and right of the string until it is at least size of len, then appends the result to the given IO.
DEPRECATED Use #center(io :IO, len : Int, char : Char = ' ')
instead
Adds instances of char to left and right of the string until it is at least size of len.
Adds instances of char to left ond right of the string until it is at least size of len, then appends the result to the given IO.
DEPRECATED Use #center(io :IO, len : Int, char : Char = ' ')
instead
Returns the Char
at the given index.
Returns the Char
at the given index, or result of running the given block if out of bounds.
Returns the byte index of a char index, or nil
if out of bounds.
Returns an Array
of all characters in the string.
Raises an ArgumentError
if self
has null bytes.
Returns a new String
with the last carriage return removed (that is, it will remove \n, \r, and \r\n).
Returns a new String
with suffix removed from the end of the string.
Returns a new String
with suffix removed from the end of the string.
Returns self
.
Returns the codepoint of the character at the given index.
Returns an Array
of the codepoints that make the string.
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.
Sets should be a list of strings following the rules described at Char#in_set?
.
Yields each char in this string to the block, returns the number of times the block returned a truthy value.
Counts the occurrences of other char in this string.
Yields each char in this string to the block.
Returns a new String
with all occurrences of char removed.
Sets should be a list of strings following the rules described at Char#in_set?
.
Returns a new String
with each uppercase letter replaced with its lowercase counterpart.
Writes a downcased version of self
to the given io.
Returns a representation of self
using character escapes for special characters and and non-ascii characters (unicode codepoints > 128), wrapped in quotes.
Appends self
to the given IO
object using character escapes for special characters and and non-ascii characters (unicode codepoints > 128), wrapped in quotes.
Returns a representation of self
using character escapes for special characters and and non-ascii characters (unicode codepoints > 128), but not wrapped in quotes.
Appends self
to the given IO
object using character escapes for special characters and and non-ascii characters (unicode codepoints > 128), but not wrapped in quotes.
Returns self
.
Yields each byte in the string to the block.
Returns an Iterator
over each byte in the string.
Returns an Iterator
over each character in the string.
Yields each character in the string to the block.
Yields each character and its index in the string to the block.
Yields each codepoint to the block.
Returns an Iterator
for each codepoint.
Splits the string after each newline and yields each line to a block.
Returns an Iterator
which yields each line of this string (see String#each_line
).
Returns true
if this is the empty string, ""
.
Returns a slice of bytes containing this string encoded in the given encoding.
Returns true
if this string ends with the given str.
Returns true
if the regular expression re matches at the end of this string.
Returns true
if this string ends with the given char.
Returns a String
where all occurrences of the given pattern are replaced with a hash of replacements.
Returns a String
where all occurrences of the given string are replaced with the block's value.
Returns a String
where each character yielded to the given block is replaced by the block's return value.
Returns a String
where all occurrences of the given char are replaced with the given replacement.
Returns a String
where all occurrences of the given pattern are replaced with the given replacement.
Returns a String
where all occurrences of the given string are replaced with the given replacement.
Returns a String
where all chars in the given hash are replaced by the corresponding hash values.
Returns a String
where all chars in the given named tuple are replaced by the corresponding tuple values.
Returns a String
where all occurrences of the given pattern are replaced by the block value's value.
This returns true
if this string has '\\'
in it.
Interprets this string as containing a sequence of hexadecimal values and decodes it as a slice of bytes.
Interprets this string as containing a sequence of hexadecimal values and decodes it as a slice of bytes.
Returns true
if the string contains search.
Returns the index of the first occurrence of search in the string, or nil
if not present.
Returns the index of the first occurrence of search in the string, or nil
if not present.
Returns the index of the first occurrence of search in the string, or nil
if not present.
Returns a new String
that results of inserting other in self
at index.
Returns a new String
that results of inserting other in self
at index.
Appends self
to the given IO
object using character escapes for special characters and wrapped in double quotes.
Returns a representation of self
using character escapes for special characters and wrapped in quotes.
Returns a representation of self
using character escapes for special characters but not wrapped in quotes.
Appends self
to the given IO
object using character escapes for special characters but not wrapped in quotes.
Returns a new String
with the first char removed from it.
Returns a new String
with prefix removed from the beginning of the string.
Returns a new String
with prefix removed from the beginning of the string if possible, else returns nil
.
Returns a new String
with the first char removed from it if possible, else returns nil
.
Adds instances of char to right of the string until it is at least size of len, and then appends the result to the given IO.
Adds spaces to right of the string until it is at least size of len, and then appends the result to the given IO.
DEPRECATED Use #ljust(io :IO, len : Int, char : Char = ' ')
instead
Adds instances of char to right of the string until it is at least size of len.
Adds instances of char to right of the string until it is at least size of len, and then appends the result to the given IO.
DEPRECATED Use #ljust(io :IO, len : Int, char : Char = ' ')
instead
Returns a new string with leading occurrences of char removed.
Returns a new string where leading occurrences of any char in chars are removed.
Returns a new string where leading characters for which the block returns a truthy value are removed.
Returns a new String
with leading whitespace removed.
Finds match of regex, starting at pos.
Returns self
unless #blank?
is true
in which case it returns nil
.
Pretty prints self
into the given printer.
Returns a new String
with the last character removed.
Returns a new String
with suffix removed from the end of the string.
Returns a new String
with the last character removed if possible, else returns nil
.
Returns a new String
with suffix removed from the end of the string if possible, else returns nil
.
Reverses the order of characters in the string.
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).
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).
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).
Adds instances of char to left of the string until it is at least size of len.
Adds instances of char to left of the string until it is at least size of len, and then appends the result to the given IO.
DEPRECATED Use #rjust(io :IO, len : Int, char : Char = ' ')
instead
Adds spaces to left of the string until it is at least size of len, and then appends the result to the given IO.
DEPRECATED Use #rjust(io :IO, len : Int, char : Char = ' ')
instead
Adds instances of char to left of the string until it is at least size of len, and then appends the result to the given IO.
Returns a new string with trailing occurrences of char removed.
Returns a new string where trailing occurrences of any char in chars are removed.
Returns a new String
with trailing whitespace removed.
Returns a new string where trailing characters for which the block returns a truthy value are removed.
Searches the string for instances of pattern, returning an array of the matched string 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 a 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.
Makes an Array
by splitting the string on separator (and removing instances of separator).
Splits the string after each regex separator and yields each part to a block.
Splits the string after each string separator and yields each part to a block.
Makes an Array
by splitting the string on separator (and removing instances of separator).
Splits the string after each character separator and yields each part to a block.
Makes an Array
by splitting the string on the given character separator (and removing that character).
Splits the string after any amount of ASCII whitespace characters and yields each non-whitespace part to a block.
Makes an array by splitting the string on any amount of ASCII whitespace characters (and removing that whitespace).
Returns a new String
, that has all characters removed, that were the same as the previous one.
Sets should be a list of strings following the rules described at Char#in_set?
.
Yields each char in this string to the block.
Returns a new String
, with all runs of char replaced by one instance.
Returns true
if this string starts with the given str.
Returns true
if this string starts with the given char.
Returns true
if the regular expression re matches at the start of this string.
Returns a new string where leading and trailing occurrences of char are removed.
Returns a new string where leading and trailing characters for which the block returns a truthy value are removed.
Returns a new String
with leading and trailing whitespace removed.
Returns a new string where leading and trailing occurrences of any char in chars are removed.
Returns a String
where the first occurrence of char is replaced by replacement.
Returns a String
where the first occurrences of the given pattern is replaced with the matching entry from the hash of replacements.
Returns a new String
where the first character is yielded to the given block and replaced by its return value.
Returns a String
where the first occurrences of the given string is replaced with the block's value.
Returns a String
where the first occurrence of pattern is replaced by the block's return value.
Returns a String
where the first occurrence of pattern is replaced by replacement
Returns a String
where the first occurrences of the given string is replaced with the given replacement.
Returns a new String
with the character at the given index replaced by replacement.
Returns a new String
with the character at the given index replaced by replacement.
Returns a new String
with characters at the given range replaced by replacement.
Returns a String
where the first char in the string matching a key in the given hash is replaced by the corresponding hash value.
Returns a new String
with characters at the given range replaced by replacement.
Returns the successor of the string.
Returns a new String
with the first letter after any space converted to uppercase and every other letter converted to lowercase.
Writes a titleized version of self
to the given io.
Converts self
to BigDecimal
.
Converts self
to a BigFloat
.
Returns a BigInt
from this string, in the given base.
Returns the result of interpreting characters in this string as a floating point number (Float64
).
Same as #to_f
but returns a Float32.
Same as #to_f?
but returns a Float32.
Same as #to_f
.
Same as #to_f?
.
Returns the result of interpreting characters in this string as a floating point number (Float64
).
Returns the result of interpreting leading characters in this string as an integer base base (between 2 and 36).
Same as #to_i
.
Same as #to_i
.
Same as #to_i
.
Returns self
.
Appends self
to io.
Returns the underlying bytes of this String.
Returns a pointer to the underlying bytes of this String.
Returns the UTF-16 encoding of the given string.
Returns a new string translating characters using from and to as a map.
Writes an underscored version of self
to the given io.
Converts camelcase boundaries to underscores.
Returns the byte at the given index without bounds checking.
Returns the underlying bytes of this String starting at given byte_offset.
Returns count of underlying bytes of this String starting at given byte_offset.
Writes a upcased version of self
to the given io.
Returns a new String
with each lowercase letter replaced with its uppercase counterpart.
Returns true
if this String is encoded correctly according to the UTF-8 encoding.
Comparable(String)
Reference
Reference
Object
Object
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"
Decodes the given slice UTF-16 sequence into a String.
Invalid values are encoded using the unicode replacement char with codepoint 0xfffd
.
slice = Slice[104_u16, 105_u16, 32_u16, 55296_u16, 56485_u16] String.from_utf16(slice) # => "hi 𐂥"
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"
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
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 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 ignoredslice = Slice.new(2, 0_u8) slice[0] = 186_u8 slice[1] = 195_u8 String.new(slice, "GB2312") # => "好"
Decodes the given slice UTF-16 sequence into a String and returns the pointer after reading. The string ends when a zero value is found.
slice = Slice[104_u16, 105_u16, 0_u16, 55296_u16, 56485_u16, 0_u16] String.from_utf16(slice) # => "hi\0000𐂥" pointer = slice.to_unsafe string, pointer = String.from_utf16(pointer) # => "hi" string, pointer = String.from_utf16(pointer) # => "𐂥"
Invalid values are encoded using the unicode replacement char with codepoint 0xfffd
.
Implementation of string interpolation of multiple, possibly non-string values.
For example, this code will end up invoking this method:
value1 = "hello" value2 = 123 "#{value1} #{value2}!" # same as String.interpolation(value1, " ", value2, "!")
In this case the implementation will call String.build
with the given values.
NOTE there should never be a need to call this method instead of using string interpolation.
Implementation of string interpolation of multiple string values.
For example, this code will end up invoking this method:
value1 = "hello" value2 = "world" "#{value1} #{value2}!" # same as String.interpolation(value1, " ", value2, "!")
In this case the implementation can pre-compute the needed string bytesize and so it's a bit more performant than interpolating non-string values.
NOTE there should never be a need to call this method instead of using string interpolation.
Implementation of string interpolation of a single non-string value.
For example, this code will end up invoking this method:
value = 123 "#{value}" # same as String.interpolation(value)
In this case the implementation just returns the result of calling value.to_s
.
NOTE there should never be a need to call this method instead of using string interpolation.
Implementation of string interpolation of a single string.
For example, this code will end up invoking this method:
value = "hello" "#{value}" # same as String.interpolation(value)
In this case the implementation just returns the same string.
NOTE there should never be a need to call this method instead of using string interpolation.
Implementation of string interpolation of a char and a string.
For example, this code will end up invoking this method:
char = '!' "#{char}hello" # same as String.interpolation(char, "hello")
In this case the implementation just does char + value
.
NOTE there should never be a need to call this method instead of using string interpolation.
Implementation of string interpolation of a string and a char.
For example, this code will end up invoking this method:
char = '!' "hello#{char}" # same as String.interpolation("hello", char)
In this case the implementation just does value + char
.
NOTE there should never be a need to call this method instead of using string interpolation.
Interpolates other into the string using Kernel#sprintf
.
"I have %d apples" % 5 # => "I have 5 apples" "%s, %s, %s, D" % ['A', 'B', 'C'] # => "A, B, C, D" "sum: %{one} + %{two} = %{three}" % {one: 1, two: 2, three: 1 + 2} # => "sum: 1 + 2 = 3" "I have %<apples>s apples" % {apples: 4} # => "I have 4 apples"
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"
The comparison operator.
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
Returns true
if this string is equal to `other. Comparison is done byte-per-byte: if a byte is different from the corresponding byte, false
is returned and so on.
See #compare
for more comparison options.
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.
start can can be negative to start counting from the end of the string.
Raises IndexError
if the start index is out of bounds.
Raises ArgumentError
if count is negative.
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 out of bounds.
"hello"[0..2] # => "hel" "hello"[0...2] # => "he" "hello"[1..-1] # => "ello" "hello"[1...-1] # => "ell" "hello"[6..7] # raises IndexError
Returns the Char
at the given index.
Negative indices can be used to start counting from the end of the string.
Raises IndexError
if the index is out of bounds.
"hello"[0] # => 'h' "hello"[1] # => 'e' "hello"[-1] # => 'o' "hello"[-2] # => 'l' "hello"[5] # raises IndexError
Like #[Int, Int]
but returns nil
if the start index is out of bounds.
Like #[Range]
, but returns nil
if the range's start is out of bounds.
"hello"[6..7]? # => nil "hello"[6..]? # => nil
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 byte at the given index.
Raises IndexError
if the index is out of bounds.
"¥hello".byte_at(0) # => 194 "¥hello".byte_at(1) # => 165 "¥hello".byte_at(2) # => 104 "¥hello".byte_at(-1) # => 111 "¥hello".byte_at(6) # => 111 "¥hello".byte_at(7) # raises IndexError
Returns the byte at the given index, or yields if out of bounds.
"¥hello".byte_at(6) { "OUT OF BOUNDS" } # => 111 "¥hello".byte_at(7) { "OUT OF BOUNDS" } # => "OUT OF BOUNDS"
Returns the byte at the given index, or nil
if out of bounds.
"¥hello".byte_at?(0) # => 194 "¥hello".byte_at?(1) # => 165 "¥hello".byte_at?(2) # => 104 "¥hello".byte_at?(-1) # => 111 "¥hello".byte_at?(6) # => 111 "¥hello".byte_at?(7) # => nil
Returns the index of the first ocurrence of byte in the string, or nil
if not present. If offset is present, it defines the position to start the search.
Negative offset can be used to start the search from the end of the string.
"Hello, World".byte_index(0x6f) # => 4 "Hello, World".byte_index(0x5a) # => nil "Hello, World".byte_index(0x6f, 5) # => 8 "💣".byte_index(0xA3) # => 3 "Dizzy Miss Lizzy".byte_index('z'.ord) # => 2 "Dizzy Miss Lizzy".byte_index('z'.ord, 3) # => 3 "Dizzy Miss Lizzy".byte_index('z'.ord, -4) # => 13 "Dizzy Miss Lizzy".byte_index('z'.ord, -17) # => nil
Returns the byte 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.
Negative offset can be used to start the search from the end of the string.
"¥hello".byte_index("hello") # => 2 "hello".byte_index("world") # => nil "Dizzy Miss Lizzy".byte_index("izzy") # => 1 "Dizzy Miss Lizzy".byte_index("izzy", 2) # => 12 "Dizzy Miss Lizzy".byte_index("izzy", -4) # => 12 "Dizzy Miss Lizzy".byte_index("izzy", -3) # => nil
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 a new string built from count bytes starting at start byte.
start can can be negative to start counting from the end of the string. If count is bigger than the number of bytes from start to #bytesize
, only remaining bytes are returned.
This method should be avoided, unless the string is proven to be ASCII-only (for example #ascii_only?
), or the byte positions are known to be at character boundaries. Otherwise, multi-byte characters may be split, leading to an invalid UTF-8 encoding.
Raises IndexError
if the start index is out of bounds.
Raises ArgumentError
if count is negative.
"hello".byte_slice(0, 2) # => "he" "hello".byte_slice(0, 100) # => "hello" "hello".byte_slice(-2, 3) # => "he" "hello".byte_slice(-2, 5) # => "he" "hello".byte_slice(-2, 5) # => "he" "¥hello".byte_slice(0, 2) # => "¥" "¥hello".byte_slice(2, 2) # => "he" "¥hello".byte_slice(0, 1) # => "�" (invalid UTF-8 character) "¥hello".byte_slice(1, 1) # => "�" (invalid UTF-8 character) "¥hello".byte_slice(1, 2) # => "�h" (invalid UTF-8 character) "hello".byte_slice(6, 2) # raises IndexError "hello".byte_slice(-6, 2) # raises IndexError "hello".byte_slice(0, -2) # raises ArgumentError
Returns a substring starting from the start byte.
start can can be negative to start counting from the end of the string.
This method should be avoided, unless the string is proven to be ASCII-only (for example #ascii_only?
), or the byte positions are known to be at character boundaries. Otherwise, multi-byte characters may be split, leading to an invalid UTF-8 encoding.
Raises IndexError
if start index is out of bounds.
"hello".byte_slice(0) # => "hello" "hello".byte_slice(2) # => "llo" "hello".byte_slice(-2) # => "lo" "¥hello".byte_slice(2) # => "hello" "¥hello".byte_slice(1) # => "�hello" (invalid UTF-8 character) "hello".byte_slice(6) # raises IndexError "hello".byte_slice(-6) # raises IndexError
Like #byte_slice(Int, Int)
but returns Nil
if the start index is out of bounds.
Raises ArgumentError
if count is negative.
"hello".byte_slice?(0, 2) # => "he" "hello".byte_slice?(0, 100) # => "hello" "hello".byte_slice?(6, 2) # => nil "hello".byte_slice?(-6, 2) # => nil "hello".byte_slice?(0, -2) # raises ArgumentError
Returns the number of bytes in this string.
"hello".bytesize # => 5 "你好".bytesize # => 6
Writes an camelcased version of self
to the given io.
If lower is true, lower camelcase will be written (the first letter is downcased).
io = IO::Memory.new "eiffel_tower".camelcase io io.to_s # => "EiffelTower"
Converts underscores to camelcase boundaries.
If lower is true, lower camelcase will be returned (the first letter is downcased).
"eiffel_tower".camelcase # => "EiffelTower" "empire_state_building".camelcase(lower: true) # => "empireStateBuilding" "isolated_integer".camelcase(options: Unicode::CaseOptions::Turkic) # => "İsolatedİnteger"
Writes a capitalized version of self
to the given io.
io = IO::Memory.new "hEllO".capitalize io io.to_s # => Hello
Returns a new String
with the first letter converted to uppercase and every subsequent letter converted to lowercase.
"hEllO".capitalize # => "Hello"
Adds instances of char to left and right of the string until it is at least size of len, then appends the result to the given IO.
io = IO::Memory.new "Purple".center(9, '-', io) io.to_s # => "-Purple--"
Adds spaces to left and right of the string until it is at least size of len, then appends the result to the given IO.
io = IO::Memory.new "Purple".center(9, io) io.to_s # => " Purple "
DEPRECATED Use #center(io :IO, len : Int, char : Char = ' ')
instead
Adds instances of char to left and right of the string until it is at least size of len.
"Purple".center(8) # => " Purple " "Purple".center(8, '-') # => "-Purple-" "Purple".center(9, '-') # => "-Purple--" "Aubergine".center(8) # => "Aubergine"
Adds instances of char to left ond right of the string until it is at least size of len, then appends the result to the given IO.
io = IO::Memory.new "Purple".center(9, '-', io) io.to_s # => "-Purple--"
DEPRECATED Use #center(io :IO, len : Int, char : Char = ' ')
instead
Returns the Char
at the given index.
Negative indices can be used to start counting from the end of the string.
Raises IndexError
if the index is out of bounds.
"hello".char_at(0) # => 'h' "hello".char_at(1) # => 'e' "hello".char_at(-1) # => 'o' "hello".char_at(-2) # => 'l' "hello".char_at(5) # raises IndexError
Returns the Char
at the given index, or result of running the given block if out of bounds.
Negative indices can be used to start counting from the end of the string.
"hello".char_at(4) { 'x' } # => 'o' "hello".char_at(5) { 'x' } # => 'x' "hello".char_at(-1) { 'x' } # => 'o' "hello".char_at(-5) { 'x' } # => 'h' "hello".char_at(-6) { 'x' } # => 'x'
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 the codepoint of the character at the given index.
Negative indices can be used to start counting from the end of the string.
Raises IndexError
if the index is out of bounds.
See also: Char#ord
.
"hello".codepoint_at(0) # => 104 "hello".codepoint_at(-1) # => 111 "hello".codepoint_at(5) # raises IndexError
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.
"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 "heIIo".compare("heııo", case_insensitive: true, options: Unicode::CaseOptions::Turkic) # => 0
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 the number of times the block returned a truthy value.
"aabbcc".count &.in?('a', 'b') # => 4
Counts the occurrences of other char in this string.
"aabbcc".count('a') # => 2
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 &.in?('a', 'b') # => "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"
Writes a downcased version of self
to the given io.
io = IO::Memory.new "hEllO".downcase io io.to_s # => hello
Returns a representation of self
using character escapes for special characters and and non-ascii characters (unicode codepoints > 128), wrapped in quotes.
"\u{1f48e} - à la carte\n".dump # => %("\\u{1F48E} - \\u00E0 la carte\\n")
Appends self
to the given IO
object using character escapes for special characters and and non-ascii characters (unicode codepoints > 128), wrapped in quotes.
Returns a representation of self
using character escapes for special characters and and non-ascii characters (unicode codepoints > 128), but not wrapped in quotes.
"\u{1f48e} - à la carte\n".dump_unquoted # => %(\\u{1F48E} - \\u00E0 la carte\\n)
Appends self
to the given IO
object using character escapes for special characters and and non-ascii characters (unicode codepoints > 128), but not wrapped in quotes.
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 byte in the string.
bytes = "ab☃".each_byte bytes.next # => 97 bytes.next # => 98 bytes.next # => 226 bytes.next # => 152 bytes.next # => 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}]
Accepts an optional offset parameter, which tells it to start counting from there.
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
.
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 end # output: # the first cold shower # even the monkey seems to want # a little coat of straw
Returns an Iterator
which yields each line of this string (see String#each_line
).
Returns true
if this is the empty string, ""
.
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 true
if this string ends with the given str.
"hello".ends_with?("o") # => true "hello".ends_with?("lo") # => true "hello".ends_with?("ll") # => false
Returns true
if the regular expression re matches at the end of this string.
"22hello".ends_with?(/[0-9]/) # => false "22hello".ends_with?(/[a-z]/) # => true "22h".ends_with?(/[a-z]/) # => true "22h".ends_with?(/[A-Z]/) # => false "22h".ends_with?(/[a-z]{2}/) # => false "22hh".ends_with?(/[a-z]{2}/) # => true
Returns true
if this string ends with the given char.
"hello".ends_with?('o') # => true "hello".ends_with?('l') # => false
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 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 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 the first occurrence of search in the string, or nil
if 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 the first occurrence of search in the string, or nil
if 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 the first occurrence of search in the string, or nil
if 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, "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
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
Appends self
to the given IO
object using character escapes for special characters and wrapped in double quotes.
Returns a representation of self
using character escapes for special characters and wrapped in quotes.
"\u{1f48e} - à la carte\n".inspect # => %("\u{1F48E} - à la carte\\n")
Returns a representation of self
using character escapes for special characters but not wrapped in quotes.
"\u{1f48e} - à la carte\n".inspect_unquoted # => %(\u{1F48E} - à la carte\\n)
Appends self
to the given IO
object using character escapes for special characters but not wrapped in quotes.
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('h') # => "ello" "hello".lchop('g') # => "hello" "hello".lchop("hel") # => "lo" "hello".lchop("eh") # => "hello"
Returns a new String
with prefix removed from the beginning of the string if possible, else returns nil
.
"hello".lchop?('h') # => "ello" "hello".lchop?('g') # => nil "hello".lchop?("hel") # => "lo" "hello".lchop?("eh") # => nil
Returns a new String
with the first char removed from it if possible, else returns nil
.
"hello".lchop? # => "ello" "".lchop? # => nil
Adds instances of char to right of the string until it is at least size of len, and then appends the result to the given IO.
io = IO::Memory.new "Purple".ljust(io, 8, '-') io.to_s # => "Purple--"
Adds spaces to right of the string until it is at least size of len, and then appends the result to the given IO.
io = IO::Memory.new "Purple".ljust(8, io) io.to_s # => "Purple "
DEPRECATED Use #ljust(io :IO, len : Int, char : Char = ' ')
instead
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"
Adds instances of char to right of the string until it is at least size of len, and then appends the result to the given IO.
io = IO::Memory.new "Purple".ljust(8, '-', io) io.to_s # => "Purple--"
DEPRECATED Use #ljust(io :IO, len : Int, char : Char = ' ')
instead
Returns a new string with leading occurrences of char removed.
"aaabcdaaa".lstrip('a') # => "bcdaaa"
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"
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
with leading whitespace removed.
" hello ".lstrip # => "hello " "\tgoodbye\r\n".lstrip # => "goodbye\r\n"
Finds match of regex, starting at pos. It also updates $~
with the result.
"foo".match(/foo/) # => Regex::MatchData("foo") $~ # => Regex::MatchData("foo") "foo".match(/bar/) # => nil $~ # raises Exception
Returns self
unless #blank?
is true
in which case it returns nil
.
"a".presence # => "a" "".presence # => nil " ".presence # => nil " a ".presence # => " a " nil.presence # => nil config = {"empty" => ""} config["empty"]?.presence || "default" # => "default" config["missing"]?.presence || "default" # => "default"
See also: Nil#presence
.
Pretty prints self
into the given printer.
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('g') # => "strin" "string".rchop('x') # => "string" "string".rchop("ing") # => "str" "string".rchop("inx") # => "string"
Returns a new String
with the last character removed if possible, else returns nil
.
"string\r\n".rchop? # => "string\r" "string\n\r".rchop? # => "string\n" "string\n".rchop? # => "string" "string".rchop? # => "strin" "".rchop? # => nil
Returns a new String
with suffix removed from the end of the string if possible, else returns nil
.
"string".rchop?('g') # => "strin" "string".rchop?('x') # => nil "string".rchop?("ing") # => "str" "string".rchop?("inx") # => nil
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"
Adds instances of char to left of the string until it is at least size of len, and then appends the result to the given IO.
io = IO::Memory.new "Purple".rjust(8, '-', io) io.to_s # => "--Purple"
DEPRECATED Use #rjust(io :IO, len : Int, char : Char = ' ')
instead
Adds spaces to left of the string until it is at least size of len, and then appends the result to the given IO.
io = IO::Memory.new "Purple".rjust(8, io) io.to_s # => " Purple"
DEPRECATED Use #rjust(io :IO, len : Int, char : Char = ' ')
instead
Adds instances of char to left of the string until it is at least size of len, and then appends the result to the given IO.
io = IO::Memory.new "Purple".rjust(8, '-', io) io.to_s # => "--Purple"
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 occurrences of char removed.
"aaabcdaaa".rstrip('a') # => "aaabcd"
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 whitespace removed.
" hello ".rstrip # => " hello" "\tgoodbye\r\n".rstrip # => "\tgoodbye"
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, returning an Array
of Regex::MatchData
for each match.
Searches the string for instances of pattern, yielding a 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.
If remove_empty is true
, any empty strings are removed from the result.
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.
If remove_empty is true
, any empty strings are removed from the result.
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.
If remove_empty is true
, any empty strings are removed from the result.
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("i", remove_empty: true) { |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 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.
If remove_empty is true
, any empty strings are removed from the result.
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("i", remove_empty: true) # => ["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.
If remove_empty is true
, any empty strings are not yielded.
ary = [] of String "foo,,bar,baz".split(',') { |string| ary << string } ary # => ["foo", "", "bar", "baz"] ary.clear "foo,,bar,baz".split(',', remove_empty: true) { |string| ary << string } ary # => ["foo", "bar", "baz"] ary.clear "foo,bar,baz".split(',', 2) { |string| ary << string } ary # => ["foo", "bar,baz"]
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.
If remove_empty is true
, any empty strings are removed from the result.
"foo,,bar,baz".split(',') # => ["foo", "", "bar", "baz"] "foo,,bar,baz".split(',', remove_empty: true) # => ["foo", "bar", "baz"] "foo,bar,baz".split(',', 2) # => ["foo", "bar,baz"]
Splits the string after any amount of ASCII whitespace characters and yields each non-whitespace 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 any amount of 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"]
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"
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 &.in?('a', 'b') # => "abccc" "aaabbbccc".squeeze &.in?('a', 'c') # => "abbbc"
Returns a new String
, with all runs of char replaced by one instance.
"a bbb".squeeze(' ') # => "a bbb"
Returns true
if this string starts with the given str.
"hello".starts_with?("h") # => true "hello".starts_with?("he") # => true "hello".starts_with?("hu") # => false
Returns true
if this string starts with the given char.
"hello".starts_with?('h') # => true "hello".starts_with?('e') # => false
Returns true
if the regular expression re matches at the start of this string.
"22hello".starts_with?(/[0-9]/) # => true "22hello".starts_with?(/[a-z]/) # => false "h22".starts_with?(/[a-z]/) # => true "h22".starts_with?(/[A-Z]/) # => false "h22".starts_with?(/[a-z]{2}/) # => false "hh22".starts_with?(/[a-z]{2}/) # => true
Returns a new string where leading and trailing occurrences of char are removed.
"aaabcdaaa".strip('a') # => "bcd"
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 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 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 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 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 the block's return value.
"hello".sub(/./) { |s| s[0].ord.to_s + ' ' } # => "104 ello"
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 string is replaced with the given replacement.
"hello yellow".sub("ll", "dd") # => "heddo yellow"
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, "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
with characters at the given range replaced by replacement.
"hello".sub(1..2, 'a') # => "halo"
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 new String
with the first letter after any space converted to uppercase and every other letter converted to lowercase.
"hEllO tAb\tworld".titleize # => "Hello Tab\tWorld" " spaces before".titleize # => " Spaces Before" "x-men: the last stand".titleize # => "X-men: The Last Stand"
Writes a titleized version of self
to the given io.
io = IO::Memory.new "x-men: the last stand".titleize io io.to_s # => X-men: The Last Stand
Converts self
to BigDecimal
.
require "big" "1212341515125412412412421".to_big_d
Returns a BigInt
from this string, in the given base.
Raises ArgumentError
if this string doesn't denote a valid integer.
require "big" "3a060dbf8d1a5ac3e67bc8f18843fc48".to_big_i(16)
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:
true
, leading and trailing whitespaces are allowedtrue
, 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
Same as #to_f
but returns a Float32.
Same as #to_f?
but returns a Float32.
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:
true
, leading and trailing whitespaces are allowedtrue
, 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
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:
true
, leading and trailing whitespaces are allowedtrue
, underscores in numbers are allowedtrue
, the prefixes "0x"
, "0o"
and "0b"
override the basetrue
, extraneous characters past the end of the number are disallowedtrue
, then a number prefixed with "0"
will be treated as an octal"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 "0755".to_i # => 755 "0755".to_i(leading_zero_is_octal: true) # => 493
Same as #to_i
.
Same as #to_i
.
Same as #to_i
.
Returns the underlying bytes of this String.
The returned slice is read-only.
Returns the UTF-16 encoding of the given string.
Invalid chars (in the range U+D800..U+DFFF) are encoded with the unicode replacement char value 0xfffd
.
The byte following the end of this slice (but not included in it) is defined to be zero. This allows passing the result of this function into C functions that expect a null-terminated UInt16*
.
"hi 𐂥".to_utf16 # => Slice[104_u16, 105_u16, 32_u16, 55296_u16, 56485_u16]
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"
Writes an underscored version of self
to the given io.
io = IO::Memory.new "DoesWhatItSaysOnTheTin".underscore io io.to_s # => "does_what_it_says_on_the_tin"
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" "InterestingImage".underscore(Unicode::CaseOptions::Turkic) # => "ınteresting_ımage"
Returns the byte at the given index without bounds checking.
Returns the underlying bytes of this String starting at given byte_offset.
The returned slice is read-only.
Returns count of underlying bytes of this String starting at given byte_offset.
The returned slice is read-only.
Writes a upcased version of self
to the given io.
io = IO::Memory.new "hEllO".upcase io io.to_s # => HELLO
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.
© 2012–2020 Manas Technology Solutions.
Licensed under the Apache License, Version 2.0.
https://crystal-lang.org/api/0.35.1/String.html