String(3) OCaml library String(3)
NAME
String - String operations.
Module
Module String
Documentation
Module String
: sig end
String operations.
A string is an immutable data structure that contains a fixed-length
sequence of (single-byte) characters. Each character can be accessed in
constant time through its index.
Given a string s of length l , we can access each of the l characters
of s via its index in the sequence. Indexes start at 0 , and we will
call an index valid in s if it falls within the range [0...l-1] (inclu-
sive). A position is the point between two characters or at the begin-
ning or end of the string. We call a position valid in s if it falls
within the range [0...l] (inclusive). Note that the character at index
n is between positions n and n+1 .
Two parameters start and len are said to designate a valid substring of
s if len >= 0 and start and start+len are valid positions in s .
OCaml strings used to be modifiable in place, for instance via the
String.set and String.blit functions described below. This usage is
deprecated and only possible when the compiler is put in
"unsafe-string" mode by giving the -unsafe-string command-line option
(which is currently the default for reasons of backward compatibility).
This is done by making the types string and bytes (see module Bytes )
interchangeable so that functions expecting byte sequences can also
accept strings as arguments and modify them.
All new code should avoid this feature and be compiled with the
-safe-string command-line option to enforce the separation between the
types string and bytes .
val length : string -> int
Return the length (number of characters) of the given string.
val get : string -> int -> char
String.get s n returns the character at index n in string s . You can
also write s.[n] instead of String.get s n .
Raise Invalid_argument if n not a valid index in s .
val set : bytes -> int -> char -> unit
Deprecated. This is a deprecated alias of Bytes.set .
String.set s n c modifies byte sequence s in place, replacing the byte
at index n with c . You can also write s.[n] <- c instead of
String.set s n c .
Raise Invalid_argument if n is not a valid index in s .
val create : int -> bytes
Deprecated. This is a deprecated alias of Bytes.create .
String.create n returns a fresh byte sequence of length n . The
sequence is uninitialized and contains arbitrary bytes.
Raise 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 .
Raise Invalid_argument if n < 0 or n > Sys.max_string_length .
val init : int -> (int -> char) -> string
String.init n f returns a string of length n , with character i ini-
tialized to the result of f i (called in increasing index order).
Raise Invalid_argument if n < 0 or n > Sys.max_string_length .
Since 4.02.0
val copy : string -> string
Deprecated. Because strings are immutable, it doesn't make much sense
to make identical copies of them.
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 , contain-
ing the substring of s that starts at position start and has length len
.
Raise Invalid_argument if start and len do not designate a valid sub-
string of s .
val fill : bytes -> int -> int -> char -> unit
Deprecated. This is a deprecated alias of Bytes.fill .
String.fill s start len c modifies byte sequence s in place, replacing
len bytes with c , starting at start .
Raise Invalid_argument if start and len do not designate a valid range
of s .
val blit : string -> int -> bytes -> int -> int -> unit
Same as Bytes.blit_string .
val concat : string -> string list -> string
String.concat sep sl concatenates the list of strings sl , inserting
the separator string sep between each.
Raise Invalid_argument if the result is longer than
Sys.max_string_length bytes.
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.
Since 4.00.0
val map : (char -> char) -> string -> string
String.map f s applies function f in turn to all the characters of s
(in increasing index order) and stores the results in a new string that
is returned.
Since 4.00.0
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.
Since 4.02.0
val trim : string -> string
Return a copy of the argument, without leading and trailing whitespace.
The characters regarded as whitespace are: ' ' , '\012' , '\n' , '\r' ,
and '\t' . If there is neither leading nor trailing whitespace charac-
ter in the argument, return the original string itself, not a copy.
Since 4.00.0
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.
Raise Invalid_argument if the result is longer than
Sys.max_string_length bytes.
val index : string -> char -> int
String.index s c returns the index of the first occurrence of character
c in string s .
Raise Not_found if c does not occur in s .
val rindex : string -> char -> int
String.rindex s c returns the index of the last occurrence of character
c in string s .
Raise Not_found if c does not occur in s .
val index_from : string -> int -> char -> int
String.index_from s i c returns the index of the first occurrence of
character c in string s after position i . String.index s c is equiva-
lent to String.index_from s 0 c .
Raise Invalid_argument if i is not a valid position in s . Raise
Not_found if c does not occur in s after position i .
val rindex_from : string -> int -> char -> int
String.rindex_from s i c returns the index 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 .
Raise Invalid_argument if i+1 is not a valid position in s . Raise
Not_found if c does not occur in s before position i+1 .
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.con-
tains_from s 0 c .
Raise 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 .
Raise 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) char-
acter 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) char-
acter set.
val capitalize : string -> string
Return a copy of the argument, with the first character set to upper-
case.
val uncapitalize : string -> string
Return a copy of the argument, with the first character set to lower-
case.
type t = 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 .
OCamldoc 2014-10-18 String(3)
ocaml 4.02.1 - Generated Tue Oct 21 06:36:10 CDT 2014