module String: BatString
val init : int -> (int -> char) -> string
init l f
returns the string of length l
with the chars
f 0 , f 1 , f 2 ... f (l-1).
Example: String.init 256 char_of_int
val is_empty : string -> bool
is_empty s
returns true
if s
is the empty string, false
otherwise.
Usually a tad faster than comparing s
with ""
.
Example (for some string s
):
if String.is_empty s then "(Empty)" else s
val length : string -> int
Return the length (number of characters) of the given string.
val get : string -> int -> char
String.get s n
returns character number n
in string s
.
You can also write s.[n]
instead of String.get s n
.
Invalid_argument
if n
not a valid character number in s
.val set : Stdlib.Bytes.t -> int -> char -> unit
String.set s n c
modifies string s
in place,
replacing the character number n
by c
.
You can also write s.[n] <- c
instead of String.set s n c
.
Invalid_argument
if n
is not a valid character number in s
.val create : int -> Stdlib.Bytes.t
String.create n
returns a fresh string of length n
.
The string initially contains arbitrary characters.
Invalid_argument
if n < 0
or n >
Sys.max_string_length
.val make : int -> char -> string
String.make n c
returns a fresh string of length n
,
filled with the character c
.
Invalid_argument
if n < 0
or n >
Sys.max_string_length
.val copy : string -> string
Return a copy of the given string.
val sub : string -> int -> int -> string
String.sub s start len
returns a fresh string of length len
,
containing the substring of s
that starts at position start
and
has length len
.
Invalid_argument
if start
and len
do not
designate a valid substring of s
.val fill : Stdlib.Bytes.t -> int -> int -> char -> unit
String.fill s start len c
modifies the byte sequence s
in
place, replacing len
characters by c
, starting at start
.
Invalid_argument
if start
and len
do not
designate a valid substring of s
.val blit : string -> int -> Stdlib.Bytes.t -> int -> int -> unit
String.blit src srcoff dst dstoff len
copies len
characters
from string src
, starting at character number srcoff
, to the
byte sequence dst
, starting at character number dstoff
.
Invalid_argument
if srcoff
and len
do not
designate a valid substring of src
, or if dstoff
and len
do not designate a valid substring of dst
.val concat : string -> string list -> string
String.concat sep sl
concatenates the list of strings sl
,
inserting the separator string sep
between each.
val iter : (char -> unit) -> string -> unit
String.iter f s
applies function f
in turn to all
the characters of s
. It is equivalent to
f s.[0]; f s.[1]; ...; f s.[String.length s - 1]; ()
.
val iteri : (int -> char -> unit) -> string -> unit
Same as String.iter
, but the
function is applied to the index of the element as first argument
(counting from 0), and the character itself as second argument.
val map : (char -> char) -> string -> string
String.map f s
applies function f
in turn to all
the characters of s
and stores the results in a new string that
is returned.
val mapi : (int -> char -> char) -> string -> string
String.mapi f s
calls f
with each character of s
and its
index (in increasing index order) and stores the results in a new
string that is returned.
val trim : string -> string
Return a copy of the argument, without leading and trailing
whitespace (according to BatChar.is_whitespace
).
The characters regarded as whitespace are: ' '
, '\n'
, '\r'
, '\t'
,
'\012'
and '\026'
. If there is no leading nor trailing whitespace
character in the argument, return the original string itself, not a copy.
val escaped : string -> string
Return a copy of the argument, with special characters represented by escape sequences, following the lexical conventions of OCaml. If there is no special character in the argument, return the original string itself, not a copy. Its inverse function is Scanf.unescaped.
val index : string -> char -> int
String.index s c
returns the character number of the first
occurrence of character c
in string s
.
Not_found
if c
does not occur in s
.val index_opt : string -> char -> int option
String.index_opt s c
returns the index of the first
occurrence of character c
in string s
, or
None
if c
does not occur in s
.
val rindex : string -> char -> int
String.rindex s c
returns the character number of the last
occurrence of character c
in string s
.
Not_found
if c
does not occur in s
.val rindex_opt : string -> char -> int option
String.rindex_opt s c
returns the index of the last occurrence
of character c
in string s
, or None
if c
does not occur in
s
.
val index_from : string -> int -> char -> int
String.index_from s i c
returns the character number of the
first occurrence of character c
in string s
after or at position i
.
String.index s c
is equivalent to String.index_from s 0 c
.
Invalid_argument
if i
is not a valid position in s
.Not_found
if c
does not occur in s
after position i
.val index_from_opt : string -> int -> char -> int option
String.index_from_opt s i c
returns the index of the
first occurrence of character c
in string s
after position i
or None
if c
does not occur in s
after position i
.
String.index_opt s c
is equivalent to String.index_from_opt s 0 c
.
Raise Invalid_argument
if i
is not a valid position in s
.
val rindex_from : string -> int -> char -> int
String.rindex_from s i c
returns the character number of the
last occurrence of character c
in string s
before position i+1
.
String.rindex s c
is equivalent to
String.rindex_from s (String.length s - 1) c
.
Invalid_argument
if i+1
is not a valid position in s
.Not_found
if c
does not occur in s
before position i+1
.val rindex_from_opt : string -> int -> char -> int option
String.rindex_from_opt s i c
returns the index of the
last occurrence of character c
in string s
before position i+1
or None
if c
does not occur in s
before position i+1
.
String.rindex_opt s c
is equivalent to
String.rindex_from_opt s (String.length s - 1) c
.
Raise Invalid_argument
if i+1
is not a valid position in s
.
val index_after_n : char -> int -> string -> int
index_after_n chr n str
returns the index of the character that
comes immediately after the n
-th occurrence of chr
in str
.
n
= 1 returns the index of
the character located immediately after the first occurrence of
chr
.n
= 0 always returns 0
.n
-th occurrence of chr
is the last character of
str
, returns the length of str
.Invalid_argument
if n < 0
.Not_found
if there are strictly less than n
occurrences of chr
in str
.val contains : string -> char -> bool
String.contains s c
tests if character c
appears in the string s
.
val contains_from : string -> int -> char -> bool
String.contains_from s start c
tests if character c
appears in s
after position start
.
String.contains s c
is equivalent to
String.contains_from s 0 c
.
Invalid_argument
if start
is not a valid position in s
.val rcontains_from : string -> int -> char -> bool
String.rcontains_from s stop c
tests if character c
appears in s
before position stop+1
.
Invalid_argument
if stop < 0
or stop+1
is not a valid
position in s
.val uppercase : string -> string
Return a copy of the argument, with all lowercase letters translated to uppercase, including accented letters of the ISO Latin-1 (8859-1) character set.
val lowercase : string -> string
Return a copy of the argument, with all uppercase letters translated to lowercase, including accented letters of the ISO Latin-1 (8859-1) character set.
val capitalize : string -> string
Return a copy of the argument, with the first character set to uppercase.
val uncapitalize : string -> string
Return a copy of the argument, with the first character set to lowercase.
val uppercase_ascii : string -> string
Return a copy of the argument, with all lowercase letters translated to uppercase, using the US-ASCII character set.
val lowercase_ascii : string -> string
Return a copy of the argument, with all uppercase letters translated to lowercase, using the US-ASCII character set.
val capitalize_ascii : string -> string
Return a copy of the argument, with the first character set to uppercase, using the US-ASCII character set.
val uncapitalize_ascii : string -> string
Return a copy of the argument, with the first character set to lowercase, using the US-ASCII character set.
typet =
string
An alias for the type of strings.
val compare : t -> t -> int
The comparison function for strings, with the same specification as
Pervasives.compare
. Along with the type t
, this function compare
allows the module String
to be passed as argument to the functors
Set.Make
and Map.Make
.
val enum : string -> char BatEnum.t
Returns an enumeration of the characters of a string. The behaviour is unspecified if the string is mutated while it is enumerated.
Examples:
"foo" |> String.enum |> List.of_enum = ['f'; 'o'; 'o']
String.enum "a b c" // ((<>) ' ') |> String.of_enum = "abc"
val of_enum : char BatEnum.t -> string
Creates a string from a character enumeration.
Example: ['f'; 'o'; 'o'] |> List.enum |> String.of_enum = "foo"
val backwards : string -> char BatEnum.t
Returns an enumeration of the characters of a string, from last to first.
Examples:
"foo" |> String.backwards |> String.of_enum = "oof"
let rev s = String.backwards s |> String.of_enum
val of_backwards : char BatEnum.t -> string
Build a string from an enumeration, starting with last character, ending with first.
Examples:
"foo" |> String.enum |> String.of_backwards = "oof"
"foo" |> String.backwards |> String.of_backwards = "foo"
let rev s = String.enum s |> String.of_backwards
val of_list : char list -> string
Converts a list of characters to a string.
Example: ['c'; 'h'; 'a'; 'r'; 's'] |> String.of_list = "chars"
val to_list : string -> char list
Converts a string to the list of its characters.
Example: String.to_list "string" |> List.interleave ';' |> String.of_list = "s;t;r;i;n;g"
val of_int : int -> string
Returns the string representation of an int.
Example: String.of_int 56 = "56" && String.of_int (-1) = "-1"
val of_float : float -> string
Returns the string representation of an float.
Example: String.of_float 1.246 = "1.246"
val of_char : char -> string
Returns a string containing one given character.
Example: String.of_char 's' = "s"
val to_int : string -> int
Returns the integer represented by the given string or
Failure
if the string does not represent an
integer. This follows OCaml's int literal rules, so "0x"
prefixes hexadecimal integers, "0o" for octal and "0b" for
binary. Underscores within the number are allowed for
readability but ignored.
Examples: String.to_int "8_480" = String.to_int "0x21_20"
try ignore(String.to_int "2,3"); false with Failure _ -> true
Failure
if the string does not represent an integer.val to_float : string -> float
Returns the float represented by the given string or
Failure
if the string does not represent a float.
Decimal points aren't required in the given string, as they are
for float literals in OCaml, but otherwise the rules for float
literals apply.
Examples: String.to_float "12.34e-1" = String.to_float "1.234"
String.to_float "1" = 1.
try ignore(String.to_float ""); false with Failure _ -> true
Failure
if the string does not represent a float.val map : (char -> char) -> string -> string
map f s
returns a string where all characters c
in s
have been
replaced by f c
.
Example: String.map Char.uppercase "Five" = "FIVE"
*
val fold_left : ('a -> char -> 'a) -> 'a -> string -> 'a
fold_left f a s
is
f (... (f (f a s.[0]) s.[1]) ...) s.[n-1]
Examples: String.fold_left (fun li c -> c::li) [] "foo" = ['o';'o';'f']
String.fold_left max 'a' "apples" = 's'
val fold_lefti : ('a -> int -> char -> 'a) -> 'a -> string -> 'a
As fold_left
, but with the index of the element as additional argument
val fold_right : (char -> 'a -> 'a) -> string -> 'a -> 'a
fold_right f s b
is
f s.[0] (f s.[1] (... (f s.[n-1] b) ...))
Examples: String.fold_right List.cons "foo" [] = ['f';'o';'o']
String.fold_right (fun c a -> if c = ' ' then a+1 else a) "a b c" 0 = 2
val fold_righti : (int -> char -> 'a -> 'a) -> string -> 'a -> 'a
As fold_right
, but with the index of the element as additional argument
val filter : (char -> bool) -> string -> string
filter f s
returns a copy of string s
in which only
characters c
such that f c = true
remain.
Example: String.filter ((<>) ' ') "a b c" = "abc"
val filter_map : (char -> char option) -> string -> string
filter_map f s
calls (f a0) (f a1).... (f an)
where a0..an
are
the characters of s
. It returns the string of characters ci
such as
f ai = Some ci
(when f
returns None
, the corresponding element of
s
is discarded).
Example: String.filter_map (function 'a'..'z' as c -> Some (Char.uppercase c) | _ -> None) "a b c" = "ABC"
val iteri : (int -> char -> unit) -> string -> unit
String.iteri f s
is equivalent to
f 0 s.[0]; f 1 s.[1]; ...; f len s.[len]
where len
is length of string s
.
Example:
let letter_positions word =
let positions = Array.make 256 [] in
let count_letter pos c =
positions.(int_of_char c) <- pos :: positions.(int_of_char c) in
String.iteri count_letter word;
Array.mapi (fun c pos -> (char_of_int c, List.rev pos)) positions
|> Array.to_list
|> List.filter (fun (c,pos) -> pos <> [])
in
letter_positions "hello" = ['e',[1]; 'h',[0]; 'l',[2;3]; 'o',[4] ]
val find : string -> string -> int
find s x
returns the starting index of the first occurrence of
string x
within string s
.
Note This implementation is optimized for short strings.
Not_found
if x
is not a substring of s
.
Example: String.find "foobarbaz" "bar" = 3
val find_from : string -> int -> string -> int
find_from s pos x
behaves as find s x
but starts searching
at position pos
. find s x
is equivalent to find_from s 0 x
.
Not_found
if not substring is foundInvalid_argument
if pos
is not a valid position in the string.
Example: String.find_from "foobarbaz" 4 "ba" = 6
val rfind : string -> string -> int
rfind s x
returns the starting index of the last occurrence
of string x
within string s
.
Note This implementation is optimized for short strings.
Not_found
if x
is not a substring of s
.
Example: String.rfind "foobarbaz" "ba" = 6
val rfind_from : string -> int -> string -> int
rfind_from s pos x
behaves as rfind s x
but starts searching
from the right at position pos + 1
. rfind s x
is equivalent to
rfind_from s (String.length s - 1) x
.
Beware, it search between the beginning of the string to
the position pos + 1
, not between pos + 1
and the end.
Not_found
if not substring is foundInvalid_argument
if pos
is not a valid position in the string.
Example: String.rfind_from "foobarbaz" 6 "ba" = 6
val find_all : string -> string -> int BatEnum.t
find_all s x
enumerates positions of s
at which x
occurs.
Example: find_all "aabaabaa" "aba" |> List.of_enum
will return
the list [1; 4]
.
val count_string : string -> string -> int
count_string s x
count how many times x
is found in s
.
val ends_with : string -> string -> bool
ends_with s x
returns true
if the string s
is ending with x
, false
otherwise.
Example: String.ends_with "foobarbaz" "rbaz" = true
val starts_with : string -> string -> bool
starts_with s x
returns true
if s
is starting with x
, false
otherwise.
Example: String.starts_with "foobarbaz" "fooz" = false
val exists : string -> string -> bool
exists str sub
returns true if sub
is a substring of str
or
false otherwise.
Example: String.exists "foobarbaz" "obar" = true
val count_char : string -> char -> int
count_char str c
returns the number of times c
is used in str
.
val lchop : ?n:int -> string -> string
Returns the same string but without the first n
characters.
By default n
is 1.
If n
is strictly less than zero
Invalid_argument.
If the string has n
or less characters, returns the empty string.
Example:
String.lchop "Weeble" = "eeble"
String.lchop ~n:3 "Weeble" = "ble"
String.lchop ~n:1000 "Weeble" = ""
val rchop : ?n:int -> string -> string
Returns the same string but without the last n
characters.
By default n
is 1.
If n
is strictly less than zero
Invalid_argument.
If the string has n
or less characters , returns the empty string.
Example:
String.rchop "Weeble" = "Weebl"
String.rchop ~n:3 "Weeble" = "Wee"
String.rchop ~n:1000 "Weeble" = ""
val chop : ?l:int -> ?r:int -> string -> string
Returns the same string but with the first l
characters
on the left and the first r
characters on the right removed.
By default, l
and r
are both 1.
chop ~l ~r s
is equivalent to lchop ~n:l (rchop ~n:r s)
.
Invalid_argument
if either l
or r
is less than zero.
Examples:
String.chop "\"Weeble\"" = "Weeble"
String.chop ~l:2 ~r:3 "01234567" = "234"
val quote : string -> string
Add quotes around a string and escape any quote or escape appearing in that string. This function is used typically when you need to generate source code from a string.
Examples:
String.quote "foo" = "\"foo\""
String.quote "\"foo\"" = "\"\\\"foo\\\"\""
String.quote "\n" = "\"\\n\""
etc.
More precisely, the returned string conforms to the OCaml syntax: if printed, it outputs a representation of the input string as an OCaml string litteral.
val left : string -> int -> string
left r len
returns the string containing the len
first
characters of r
. If r
contains less than len
characters, it
returns r
.
Examples:
String.left "Weeble" 4 = "Weeb"
String.left "Weeble" 0 = ""
String.left "Weeble" 10 = "Weeble"
val right : string -> int -> string
right r len
returns the string containing the len
last characters of r
.
If r
contains less than len
characters, it returns r
.
Example: String.right "Weeble" 4 = "eble"
val head : string -> int -> string
val tail : string -> int -> string
tail r pos
returns the string containing all but the pos
first characters of r
Example: String.tail "Weeble" 4 = "le"
val strip : ?chars:string -> string -> string
Returns the string without the chars if they are at the beginning or at the end of the string. By default chars are " \t\r\n".
Examples:
String.strip " foo " = "foo"
String.strip ~chars:" ,()" " boo() bar()" = "boo() bar"
val replace_chars : (char -> string) -> string -> string
replace_chars f s
returns a string where all chars c
of s
have been
replaced by the string returned by f c
.
Example: String.replace_chars (function ' ' -> "(space)" | c -> String.of_char c) "foo bar" = "foo(space)bar"
val replace : str:string -> sub:string -> by:string -> bool * string
replace ~str ~sub ~by
returns a tuple consisting of a boolean
and a string where the first occurrence of the string sub
within str
has been replaced by the string by
. The boolean
is true if a substitution has taken place.
Example: String.replace "foobarbaz" "bar" "rab" = (true, "foorabbaz")
val nreplace : str:string -> sub:string -> by:string -> string
nreplace ~str ~sub ~by
returns a string obtained by iteratively
replacing each occurrence of sub
by by
in str
, from right to left.
It returns a copy of str
if sub
has no occurrence in str
.
Example: nreplace ~str:"bar foo aaa bar" ~sub:"aa" ~by:"foo" = "bar foo afoo bar"
val repeat : string -> int -> string
repeat s n
returns s ^ s ^ ... ^ s
Example: String.repeat "foo" 4 = "foofoofoofoo"
val rev : string -> string
rev s
returns the reverse of string s
val rev_in_place : Stdlib.Bytes.t -> unit
rev_in_place s
mutates the byte sequence s
, so that its new value is
the mirror of its old one: for instance if s contained "Example!"
, after
the mutation it will contain "!elpmaxE"
.
val in_place_mirror : Stdlib.Bytes.t -> unit
String.rev_in_place
insteadval split_on_char : char -> string -> string list
String.split_on_char sep s
returns the list of all (possibly empty)
substrings of s
that are delimited by the sep
character.
The function's output is specified by the following invariants:
sep
as a separator returns a
string equal to the input (String.concat (String.make 1 sep)
(String.split_on_char sep s) = s
).sep
character.Note: prior to 2.11.0 split_on_char _ ""
used to return an empty list.
val split : string -> by:string -> string * string
split s sep
splits the string s
between the first
occurrence of sep
, and returns the two parts before
and after the occurrence (excluded).
Not_found
if the separator is not found.
Examples:
String.split "abcabcabc" "bc" = ("a","abcabc")
String.split "abcabcabc" "" = ("","abcabcabc")
val rsplit : string -> by:string -> string * string
rsplit s sep
splits the string s
between the last occurrence
of sep
, and returns the two parts before and after the
occurrence (excluded).
Not_found
if the separator is not found.
Example: String.rsplit "abcabcabc" "bc" = ("abcabca","")
val nsplit : string -> by:string -> string list
BatString.split_on_string
nsplit s sep
splits the string s
into a list of strings
which are separated by sep
(excluded).
nsplit "" _
returns a single empty string.
Note: prior to 2.11.0 nsplit "" _
used to return an empty list.
Example: String.nsplit "abcabcabc" "bc" = ["a"; "a"; "a"; ""]
val split_on_string : by:string -> string -> string list
split_on_string sep s
splits the string s
into a list of strings
which are separated by sep
(excluded).
split_on_string _ ""
returns a single empty string.
Note: split_on_string sep s
is identical to nsplit s sep
but for empty strings.
Example: String.split_on_string "bc" "abcabcabc" = ["a"; "a"; "a"; ""]
val cut_on_char : char -> int -> string -> string
Similar to Unix cut
. cut_on_char chr n str
returns the substring of
str
located strictly between the n
-th occurrence of chr
and
the n+1
-th one.
chr
are numbered from 1.n = 0
, returns the substring from the beginning of
str
to the first occurrence of chr
.n
occurrences of chr
in str
, returns the
substring between the last occurrence of chr
and the end of str
.n
equals 0
and chr
is
absent from str
, returns the full string str
.Remark: cut_on_char
can return the empty string. Examples of this
behaviour are cut_on_char ',' 1 "foo,,bar"
and cut_on_char ',' 0 ",foo"
.
Not_found
if there are strictly less than n
occurrences of chr
in str.Invalid_argument
if n < 0
.val join : string -> string list -> string
Same as BatString.concat
val slice : ?first:int -> ?last:int -> string -> string
slice ?first ?last s
returns a "slice" of the string
which corresponds to the characters s.[first]
,
s.[first+1]
, ..., s[last-1]
. Note that the character at
index last
is not included! If first
is omitted it
defaults to the start of the string, i.e. index 0, and if
last
is omitted is defaults to point just past the end of
s
, i.e. length s
. Thus, slice s
is equivalent to
copy s
.
Negative indexes are interpreted as counting from the end of
the string. For example, slice ~last:(-2) s
will return the
string s
, but without the last two characters.
This function never raises any exceptions. If the indexes are out of bounds they are automatically clipped.
Example: String.slice ~first:1 ~last:(-3) " foo bar baz" = "foo bar "
val splice : string -> int -> int -> string -> string
String.splice s off len rep
cuts out the section of s
indicated by off
and len
and replaces it by rep
Negative indexes are interpreted as counting from the end
of the string. If off+len
is greater than length s
,
the end of the string is used, regardless of the value of
len
.
If len
is zero or negative, rep
is inserted at position
off
without replacing any of s
.
Example: String.splice "foo bar baz" 3 5 "XXX" = "fooXXXbaz"
val explode : string -> char list
explode s
returns the list of characters in the string s
.
Example: String.explode "foo" = ['f'; 'o'; 'o']
val implode : char list -> string
implode cs
returns a string resulting from concatenating
the characters in the list cs
.
Example: String.implode ['b'; 'a'; 'r'] = "bar"
val to_seq : t -> char Stdlib.Seq.t
Iterate on the string, in increasing index order. Modifications of the string during iteration will be reflected in the iterator.
val to_seqi : t -> (int * char) Stdlib.Seq.t
Iterate on the string, in increasing order, yielding indices along chars
val of_seq : char Stdlib.Seq.t -> t
Create a string from the generator
val equal : t -> t -> bool
String equality
val ord : t -> t -> BatOrd.order
Ordering function for strings, see BatOrd
val compare : t -> t -> int
The comparison function for strings, with the same specification as
Pervasives.compare
. Along with the type t
, this function compare
allows the module String
to be passed as argument to the functors
Set.Make
and Map.Make
.
Example: String.compare "FOO" "bar" = -1
i.e. "FOO" < "bar"
val icompare : t -> t -> int
Compare two strings, case-insensitive.
Example: String.icompare "FOO" "bar" = 1
i.e. "foo" > "bar"
module IString:BatInterfaces.OrderedType
with type t = t
uses icompare as ordering function
val numeric_compare : t -> t -> int
Compare two strings, sorting "abc32def" before "abc210abc".
Algorithm: splits both strings into lists of (strings of digits) or
(strings of non digits) (["abc"; "32"; "def"]
and ["abc"; "210"; "abc"]
)
Then both lists are compared lexicographically by comparing elements
numerically when both are numbers or lexicographically in other cases.
Example: String.numeric_compare "xx32" "xx210" < 0
module NumString:BatInterfaces.OrderedType
with type t = t
uses numeric_compare as its ordering function
val edit_distance : t -> t -> int
Edition distance (also known as "Levenshtein distance"). See wikipedia
val print : 'a BatInnerIO.output -> string -> unit
Print a string.
Example: String.print stdout "foo\n"
val println : 'a BatInnerIO.output -> string -> unit
Print a string, end the line.
Example: String.println stdout "foo"
val print_quoted : 'a BatInnerIO.output -> string -> unit
Print a string, with quotes as added by the quote
function.
String.print_quoted stdout "foo"
prints "foo"
(with the quotes).
String.print_quoted stdout "\"bar\""
prints "\"bar\""
(with the quotes).
String.print_quoted stdout "\n"
prints "\n"
(not the escaped
character, but '\'
then 'n'
).
module Exceptionless:sig
..end
Exceptionless counterparts for error-raising operations
module Cap:sig
..end
Capabilities for strings.