Module StdLabels.String
module String: StringLabels
Strings
type t = string
The type for strings.
val make : int -> char -> string
make n c
is a string of length n
with each index holding the character c
.
-
Raises
Invalid_argument
ifn < 0
orn >
Sys.max_string_length
.
val init : int -> f:(int -> char) -> string
init n ~f
is a string of length n
with index i
holding the character f i
(called in increasing index order).
- Since 4.02.0
-
Raises
Invalid_argument
ifn < 0
orn >
Sys.max_string_length
.
val empty : string
The empty string.
- Since 4.13.0
val of_bytes : bytes -> string
Return a new string that contains the same bytes as the given byte sequence.
- Since 4.13.0
val to_bytes : string -> bytes
Return a new byte sequence that contains the same bytes as the given string.
- Since 4.13.0
val length : string -> int
length s
is the length (number of bytes/characters) of s
.
val get : string -> int -> char
get s i
is the character at index i
in s
. This is the same as writing s.[i]
.
-
Raises
Invalid_argument
ifi
not an index ofs
.
Concatenating
Note. The (^)
binary operator concatenates two strings.
val concat : sep:string -> string list -> string
concat ~sep ss
concatenates the list of strings ss
, inserting the separator string sep
between each.
-
Raises
Invalid_argument
if the result is longer thanSys.max_string_length
bytes.
val cat : string -> string -> string
cat s1 s2
concatenates s1 and s2 (s1 ^ s2
).
- Since 4.13.0
-
Raises
Invalid_argument
if the result is longer then thanSys.max_string_length
bytes.
Predicates and comparisons
val equal : t -> t -> bool
equal s0 s1
is true
if and only if s0
and s1
are character-wise equal.
- Since 4.05.0
val compare : t -> t -> int
compare s0 s1
sorts s0
and s1
in lexicographical order. compare
behaves like compare
on strings but may be more efficient.
val starts_with : prefix:string -> string -> bool
starts_with
~
prefix s
is true
if and only if s
starts with prefix
.
- Since 4.13.0
val ends_with : suffix:string -> string -> bool
ends_with ~suffix s
is true
if and only if s
ends with suffix
.
- Since 4.13.0
val contains_from : string -> int -> char -> bool
contains_from s start c
is true
if and only if c
appears in s
after position start
.
-
Raises
Invalid_argument
ifstart
is not a valid position ins
.
val rcontains_from : string -> int -> char -> bool
rcontains_from s stop c
is true
if and only if c
appears in s
before position stop+1
.
-
Raises
Invalid_argument
ifstop < 0
orstop+1
is not a valid position ins
.
val contains : string -> char -> bool
contains s c
is String.contains_from
s 0 c
.
Extracting substrings
val sub : string -> pos:int -> len:int -> string
sub s ~pos ~len
is a string of length len
, containing the substring of s
that starts at position pos
and has length len
.
-
Raises
Invalid_argument
ifpos
andlen
do not designate a valid substring ofs
.
val split_on_char : sep:char -> string -> string list
split_on_char ~sep s
is the list of all (possibly empty) substrings of s
that are delimited by the character sep
.
The function's result is specified by the following invariants:
- The list is not empty.
- Concatenating its elements using
sep
as a separator returns a string equal to the input (concat (make 1 sep)
).
(split_on_char sep s) = s - No string in the result contains the
sep
character.
- Since 4.05.0
Transforming
val map : f:(char -> char) -> string -> string
map f s
is the string resulting from applying f
to all the characters of s
in increasing order.
- Since 4.00.0
val mapi : f:(int -> char -> char) -> string -> string
mapi ~f s
is like StringLabels.map
but the index of the character is also passed to f
.
- Since 4.02.0
val fold_left : f:('a -> char -> 'a) -> init:'a -> string -> 'a
fold_left f x s
computes f (... (f (f x s.[0]) s.[1]) ...) s.[n-1]
, where n
is the length of the string s
.
- Since 4.13.0
val fold_right : f:(char -> 'a -> 'a) -> string -> init:'a -> 'a
fold_right f s x
computes f s.[0] (f s.[1] ( ... (f s.[n-1] x) ...))
, where n
is the length of the string s
.
- Since 4.13.0
val for_all : f:(char -> bool) -> string -> bool
for_all p s
checks if all characters in s
satisfy the predicate p
.
- Since 4.13.0
val exists : f:(char -> bool) -> string -> bool
exists p s
checks if at least one character of s
satisfies the predicate p
.
- Since 4.13.0
val trim : string -> string
trim s
is s
without leading and trailing whitespace. Whitespace characters are: ' '
, '\x0C'
(form feed), '\n'
, '\r'
, and '\t'
.
- Since 4.00.0
val escaped : string -> string
escaped s
is s
with special characters represented by escape sequences, following the lexical conventions of OCaml.
All characters outside the US-ASCII printable range [0x20;0x7E] are escaped, as well as backslash (0x2F) and double-quote (0x22).
The function Scanf.unescaped
is a left inverse of escaped
, i.e. Scanf.unescaped (escaped s) = s
for any string s
(unless escaped s
fails).
-
Raises
Invalid_argument
if the result is longer thanSys.max_string_length
bytes.
val uppercase_ascii : string -> string
uppercase_ascii s
is s
with all lowercase letters translated to uppercase, using the US-ASCII character set.
- Since 4.05.0
val lowercase_ascii : string -> string
lowercase_ascii s
is s
with all uppercase letters translated to lowercase, using the US-ASCII character set.
- Since 4.05.0
val capitalize_ascii : string -> string
capitalize_ascii s
is s
with the first character set to uppercase, using the US-ASCII character set.
- Since 4.05.0
val uncapitalize_ascii : string -> string
uncapitalize_ascii s
is s
with the first character set to lowercase, using the US-ASCII character set.
- Since 4.05.0
Traversing
val iter : f:(char -> unit) -> string -> unit
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.[length s - 1]; ()
.
val iteri : f:(int -> char -> unit) -> string -> unit
iteri
is like StringLabels.iter
, but the function is also given the corresponding character index.
- Since 4.00.0
Searching
val index_from : string -> int -> char -> int
index_from s i c
is the index of the first occurrence of c
in s
after position i
.
-
Raises
-
Not_found
ifc
does not occur ins
after positioni
. -
Invalid_argument
ifi
is not a valid position ins
.
-
val index_from_opt : string -> int -> char -> int option
index_from_opt s i c
is the index of the first occurrence of c
in s
after position i
(if any).
- Since 4.05
-
Raises
Invalid_argument
ifi
is not a valid position ins
.
val rindex_from : string -> int -> char -> int
rindex_from s i c
is the index of the last occurrence of c
in s
before position i+1
.
-
Raises
-
Not_found
ifc
does not occur ins
before positioni+1
. -
Invalid_argument
ifi+1
is not a valid position ins
.
-
val rindex_from_opt : string -> int -> char -> int option
rindex_from_opt s i c
is the index of the last occurrence of c
in s
before position i+1
(if any).
- Since 4.05
-
Raises
Invalid_argument
ifi+1
is not a valid position ins
.
val index : string -> char -> int
index s c
is String.index_from
s 0 c
.
val index_opt : string -> char -> int option
index_opt s c
is String.index_from_opt
s 0 c
.
- Since 4.05
val rindex : string -> char -> int
rindex s c
is String.rindex_from
s (length s - 1) c
.
val rindex_opt : string -> char -> int option
rindex_opt s c
is String.rindex_from_opt
s (length s - 1) c
.
- Since 4.05
Strings and Sequences
val to_seq : t -> char Seq.t
to_seq s
is a sequence made of the string's characters in increasing order. In "unsafe-string"
mode, modifications of the string during iteration will be reflected in the sequence.
- Since 4.07
val to_seqi : t -> (int * char) Seq.t
to_seqi s
is like StringLabels.to_seq
but also tuples the corresponding index.
- Since 4.07
val of_seq : char Seq.t -> t
of_seq s
is a string made of the sequence's characters.
- Since 4.07
Deprecated functions
val create : int -> bytes
create n
returns a fresh byte sequence of length n
. The sequence is uninitialized and contains arbitrary bytes.
-
Raises
Invalid_argument
ifn < 0
orn >
Sys.max_string_length
.
val set : bytes -> int -> char -> unit
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 set s n c
.
-
Raises
Invalid_argument
ifn
is not a valid index ins
.
val blit : src:string -> src_pos:int -> dst:bytes -> dst_pos:int -> len:int -> unit
blit ~src ~src_pos ~dst ~dst_pos ~len
copies len
bytes from the string src
, starting at index src_pos
, to byte sequence dst
, starting at character number dst_pos
.
-
Raises
Invalid_argument
ifsrc_pos
andlen
do not designate a valid range ofsrc
, or ifdst_pos
andlen
do not designate a valid range ofdst
.
val copy : string -> string
Return a copy of the given string.
val fill : bytes -> pos:int -> len:int -> char -> unit
fill s ~pos ~len c
modifies byte sequence s
in place, replacing len
bytes by c
, starting at pos
.
-
Raises
Invalid_argument
ifpos
andlen
do not designate a valid substring ofs
.
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, using the ISO Latin-1 (8859-1) character set..
val uncapitalize : string -> string
Return a copy of the argument, with the first character set to lowercase, using the ISO Latin-1 (8859-1) character set.
Binary decoding of integers
The functions in this section binary decode integers from strings.
All following functions raise Invalid_argument
if the characters needed at index i
to decode the integer are not available.
Little-endian (resp. big-endian) encoding means that least (resp. most) significant bytes are stored first. Big-endian is also known as network byte order. Native-endian encoding is either little-endian or big-endian depending on Sys.big_endian
.
32-bit and 64-bit integers are represented by the int32
and int64
types, which can be interpreted either as signed or unsigned numbers.
8-bit and 16-bit integers are represented by the int
type, which has more bits than the binary encoding. These extra bits are sign-extended (or zero-extended) for functions which decode 8-bit or 16-bit integers and represented them with int
values.
val get_uint8 : string -> int -> int
get_uint8 b i
is b
's unsigned 8-bit integer starting at character index i
.
- Since 4.13.0
val get_int8 : string -> int -> int
get_int8 b i
is b
's signed 8-bit integer starting at character index i
.
- Since 4.13.0
val get_uint16_ne : string -> int -> int
get_uint16_ne b i
is b
's native-endian unsigned 16-bit integer starting at character index i
.
- Since 4.13.0
val get_uint16_be : string -> int -> int
get_uint16_be b i
is b
's big-endian unsigned 16-bit integer starting at character index i
.
- Since 4.13.0
val get_uint16_le : string -> int -> int
get_uint16_le b i
is b
's little-endian unsigned 16-bit integer starting at character index i
.
- Since 4.13.0
val get_int16_ne : string -> int -> int
get_int16_ne b i
is b
's native-endian signed 16-bit integer starting at character index i
.
- Since 4.13.0
val get_int16_be : string -> int -> int
get_int16_be b i
is b
's big-endian signed 16-bit integer starting at character index i
.
- Since 4.13.0
val get_int16_le : string -> int -> int
get_int16_le b i
is b
's little-endian signed 16-bit integer starting at character index i
.
- Since 4.13.0
val get_int32_ne : string -> int -> int32
get_int32_ne b i
is b
's native-endian 32-bit integer starting at character index i
.
- Since 4.13.0
val get_int32_be : string -> int -> int32
get_int32_be b i
is b
's big-endian 32-bit integer starting at character index i
.
- Since 4.13.0
val get_int32_le : string -> int -> int32
get_int32_le b i
is b
's little-endian 32-bit integer starting at character index i
.
- Since 4.13.0
val get_int64_ne : string -> int -> int64
get_int64_ne b i
is b
's native-endian 64-bit integer starting at character index i
.
- Since 4.13.0
val get_int64_be : string -> int -> int64
get_int64_be b i
is b
's big-endian 64-bit integer starting at character index i
.
- Since 4.13.0
val get_int64_le : string -> int -> int64
get_int64_le b i
is b
's little-endian 64-bit integer starting at character index i
.
- Since 4.13.0
© 1995-2021 INRIA.
https://www.ocaml.org/releases/4.13/htmlman/libref/StdLabels.String.html