1Stdlib.String(3) OCaml library Stdlib.String(3)
2
6 Stdlib.String - no description
7
9 Module Stdlib.String
10
12 Module String
13 : (module Stdlib__String)
14 Strings
24 type t = string
25 The type for strings.
28 val make : int -> char -> string
32 make n c is a string of length n with each index holding the character
35 c .
36 Raises Invalid_argument if n < 0 or n > Sys.max_string_length .
39 val init : int -> (int -> char) -> string
43 init n f is a string of length n with index i holding the character f i
46 (called in increasing index order).
47 Since 4.02.0
50 Raises Invalid_argument if n < 0 or n > Sys.max_string_length .
53 val empty : string
57 The empty string.
59 Since 4.13.0
62 val of_bytes : bytes -> string
66 Return a new string that contains the same bytes as the given byte se‐
68 quence.
69 Since 4.13.0
72 val to_bytes : string -> bytes
76 Return a new byte sequence that contains the same bytes as the given
78 string.
79 Since 4.13.0
82 val length : string -> int
86 length s is the length (number of bytes/characters) of s .
89 val get : string -> int -> char
93 get s i is the character at index i in s . This is the same as writing
96 s.[i] .
97 Raises Invalid_argument if i not an index of s .
100 Concatenating
105 Note. The (^) binary operator concatenates two strings.
106 val concat : string -> string list -> string
108 concat sep ss concatenates the list of strings ss , inserting the sepa‐
111 rator string sep between each.
112 Raises Invalid_argument if the result is longer than
115 Sys.max_string_length bytes.
116 val cat : string -> string -> string
120 cat s1 s2 concatenates s1 and s2 ( s1 ^ s2 ).
123 Since 4.13.0
126 Raises Invalid_argument if the result is longer than
129 Sys.max_string_length bytes.
130 Predicates and comparisons
135 val equal : t -> t -> bool
136 equal s0 s1 is true if and only if s0 and s1 are character-wise equal.
139 Since 4.03.0 (4.05.0 in StringLabels)
142 val compare : t -> t -> int
146 compare s0 s1 sorts s0 and s1 in lexicographical order. compare be‐
149 haves like compare on strings but may be more efficient.
150 val starts_with : prefix:string -> string -> bool
154 starts_with ~prefix s is true if and only if s starts with prefix .
157 Since 4.13.0
160 val ends_with : suffix:string -> string -> bool
164 ends_with ~suffix s is true if and only if s ends with suffix .
167 Since 4.13.0
170 val contains_from : string -> int -> char -> bool
174 contains_from s start c is true if and only if c appears in s after po‐
177 sition start .
178 Raises Invalid_argument if start is not a valid position in s .
181 val rcontains_from : string -> int -> char -> bool
185 rcontains_from s stop c is true if and only if c appears in s before
188 position stop+1 .
189 Raises Invalid_argument if stop < 0 or stop+1 is not a valid position
192 in s .
193 val contains : string -> char -> bool
197 contains s c is String.contains_from s 0 c .
200 Extracting substrings
205 val sub : string -> int -> int -> string
206 sub s pos len is a string of length len , containing the substring of s
209 that starts at position pos and has length len .
210 Raises Invalid_argument if pos and len do not designate a valid sub‐
213 string of s .
214 val split_on_char : char -> string -> string list
218 split_on_char sep s is the list of all (possibly empty) substrings of s
221 that are delimited by the character sep .
222 The function's result is specified by the following invariants:
224 -The list is not empty.
226 -Concatenating its elements using sep as a separator returns a string
228 equal to the input ( concat (make 1 sep)
229 (split_on_char sep s) = s ).
230 -No string in the result contains the sep character.
232 Since 4.04.0 (4.05.0 in StringLabels)
236 Transforming
241 val map : (char -> char) -> string -> string
242 map f s is the string resulting from applying f to all the characters
245 of s in increasing order.
246 Since 4.00.0
249 val mapi : (int -> char -> char) -> string -> string
253 mapi f s is like String.map but the index of the character is also
256 passed to f .
257 Since 4.02.0
260 val fold_left : ('a -> char -> 'a) -> 'a -> string -> 'a
264 fold_left f x s computes f (... (f (f x s.[0]) s.[1]) ...) s.[n-1] ,
267 where n is the length of the string s .
268 Since 4.13.0
271 val fold_right : (char -> 'a -> 'a) -> string -> 'a -> 'a
275 fold_right f s x computes f s.[0] (f s.[1] ( ... (f s.[n-1] x) ...)) ,
278 where n is the length of the string s .
279 Since 4.13.0
282 val for_all : (char -> bool) -> string -> bool
286 for_all p s checks if all characters in s satisfy the predicate p .
289 Since 4.13.0
292 val exists : (char -> bool) -> string -> bool
296 exists p s checks if at least one character of s satisfies the predi‐
299 cate p .
300 Since 4.13.0
303 val trim : string -> string
307 trim s is s without leading and trailing whitespace. Whitespace charac‐
310 ters are: ' ' , '\x0C' (form feed), '\n' , '\r' , and '\t' .
311 Since 4.00.0
314 val escaped : string -> string
318 escaped s is s with special characters represented by escape sequences,
321 following the lexical conventions of OCaml.
322 All characters outside the US-ASCII printable range [0x20;0x7E] are es‐
324 caped, as well as backslash (0x2F) and double-quote (0x22).
325 The function Scanf.unescaped is a left inverse of escaped , i.e.
327 Scanf.unescaped (escaped s) = s for any string s (unless escaped s
328 fails).
329 Raises Invalid_argument if the result is longer than
332 Sys.max_string_length bytes.
333 val uppercase_ascii : string -> string
337 uppercase_ascii s is s with all lowercase letters translated to upper‐
340 case, using the US-ASCII character set.
341 Since 4.03.0 (4.05.0 in StringLabels)
344 val lowercase_ascii : string -> string
348 lowercase_ascii s is s with all uppercase letters translated to lower‐
351 case, using the US-ASCII character set.
352 Since 4.03.0 (4.05.0 in StringLabels)
355 val capitalize_ascii : string -> string
359 capitalize_ascii s is s with the first character set to uppercase, us‐
362 ing the US-ASCII character set.
363 Since 4.03.0 (4.05.0 in StringLabels)
366 val uncapitalize_ascii : string -> string
370 uncapitalize_ascii s is s with the first character set to lowercase,
373 using the US-ASCII character set.
374 Since 4.03.0 (4.05.0 in StringLabels)
377 Traversing
382 val iter : (char -> unit) -> string -> unit
383 iter f s applies function f in turn to all the characters of s . It is
386 equivalent to f s.[0]; f s.[1]; ...; f s.[length s - 1]; () .
387 val iteri : (int -> char -> unit) -> string -> unit
391 iteri is like String.iter , but the function is also given the corre‐
394 sponding character index.
395 Since 4.00.0
398 Searching
403 val index_from : string -> int -> char -> int
404 index_from s i c is the index of the first occurrence of c in s after
407 position i .
408 Raises Not_found if c does not occur in s after position i .
411 Raises Invalid_argument if i is not a valid position in s .
414 val index_from_opt : string -> int -> char -> int option
418 index_from_opt s i c is the index of the first occurrence of c in s af‐
421 ter position i (if any).
422 Since 4.05
425 Raises Invalid_argument if i is not a valid position in s .
428 val rindex_from : string -> int -> char -> int
432 rindex_from s i c is the index of the last occurrence of c in s before
435 position i+1 .
436 Raises Not_found if c does not occur in s before position i+1 .
439 Raises Invalid_argument if i+1 is not a valid position in s .
442 val rindex_from_opt : string -> int -> char -> int option
446 rindex_from_opt s i c is the index of the last occurrence of c in s be‐
449 fore position i+1 (if any).
450 Since 4.05
453 Raises Invalid_argument if i+1 is not a valid position in s .
456 val index : string -> char -> int
460 index s c is String.index_from s 0 c .
463 val index_opt : string -> char -> int option
467 index_opt s c is String.index_from_opt s 0 c .
470 Since 4.05
473 val rindex : string -> char -> int
477 rindex s c is String.rindex_from s (length s - 1) c .
480 val rindex_opt : string -> char -> int option
484 rindex_opt s c is String.rindex_from_opt s (length s - 1) c .
487 Since 4.05
490 Strings and Sequences
495 val to_seq : t -> char Seq.t
496 to_seq s is a sequence made of the string's characters in increasing
499 order. In "unsafe-string" mode, modifications of the string during it‐
500 eration will be reflected in the sequence.
501 Since 4.07
504 val to_seqi : t -> (int * char) Seq.t
508 to_seqi s is like String.to_seq but also tuples the corresponding in‐
511 dex.
512 Since 4.07
515 val of_seq : char Seq.t -> t
519 of_seq s is a string made of the sequence's characters.
522 Since 4.07
525 UTF decoding and validations
530 UTF-8
531 val get_utf_8_uchar : t -> int -> Uchar.utf_decode
532 get_utf_8_uchar b i decodes an UTF-8 character at index i in b .
535 val is_valid_utf_8 : t -> bool
539 is_valid_utf_8 b is true if and only if b contains valid UTF-8 data.
542 UTF-16BE
547 val get_utf_16be_uchar : t -> int -> Uchar.utf_decode
548 get_utf_16be_uchar b i decodes an UTF-16BE character at index i in b .
551 val is_valid_utf_16be : t -> bool
555 is_valid_utf_16be b is true if and only if b contains valid UTF-16BE
558 data.
559 UTF-16LE
564 val get_utf_16le_uchar : t -> int -> Uchar.utf_decode
565 get_utf_16le_uchar b i decodes an UTF-16LE character at index i in b .
568 val is_valid_utf_16le : t -> bool
572 is_valid_utf_16le b is true if and only if b contains valid UTF-16LE
575 data.
576 val blit : string -> int -> bytes -> int -> int -> unit
580 blit src src_pos dst dst_pos len copies len bytes from the string src ,
583 starting at index src_pos , to byte sequence dst , starting at charac‐
584 ter number dst_pos .
585 Raises Invalid_argument if src_pos and len do not designate a valid
588 range of src , or if dst_pos and len do not designate a valid range of
589 dst .
590 Binary decoding of integers
595 The functions in this section binary decode integers from strings.
596 All following functions raise Invalid_argument if the characters needed
598 at index i to decode the integer are not available.
599 Little-endian (resp. big-endian) encoding means that least (resp. most)
601 significant bytes are stored first. Big-endian is also known as net‐
602 work byte order. Native-endian encoding is either little-endian or
603 big-endian depending on Sys.big_endian .
604 32-bit and 64-bit integers are represented by the int32 and int64
606 types, which can be interpreted either as signed or unsigned numbers.
607 8-bit and 16-bit integers are represented by the int type, which has
609 more bits than the binary encoding. These extra bits are sign-extended
610 (or zero-extended) for functions which decode 8-bit or 16-bit integers
611 and represented them with int values.
612 val get_uint8 : string -> int -> int
614 get_uint8 b i is b 's unsigned 8-bit integer starting at character in‐
617 dex i .
618 Since 4.13.0
621 val get_int8 : string -> int -> int
625 get_int8 b i is b 's signed 8-bit integer starting at character index i
628 .
629 Since 4.13.0
632 val get_uint16_ne : string -> int -> int
636 get_uint16_ne b i is b 's native-endian unsigned 16-bit integer start‐
639 ing at character index i .
640 Since 4.13.0
643 val get_uint16_be : string -> int -> int
647 get_uint16_be b i is b 's big-endian unsigned 16-bit integer starting
650 at character index i .
651 Since 4.13.0
654 val get_uint16_le : string -> int -> int
658 get_uint16_le b i is b 's little-endian unsigned 16-bit integer start‐
661 ing at character index i .
662 Since 4.13.0
665 val get_int16_ne : string -> int -> int
669 get_int16_ne b i is b 's native-endian signed 16-bit integer starting
672 at character index i .
673 Since 4.13.0
676 val get_int16_be : string -> int -> int
680 get_int16_be b i is b 's big-endian signed 16-bit integer starting at
683 character index i .
684 Since 4.13.0
687 val get_int16_le : string -> int -> int
691 get_int16_le b i is b 's little-endian signed 16-bit integer starting
694 at character index i .
695 Since 4.13.0
698 val get_int32_ne : string -> int -> int32
702 get_int32_ne b i is b 's native-endian 32-bit integer starting at char‐
705 acter index i .
706 Since 4.13.0
709 val hash : t -> int
713 An unseeded hash function for strings, with the same output value as
715 Hashtbl.hash . This function allows this module to be passed as argu‐
716 ment to the functor Hashtbl.Make .
717 Since 5.0.0
720 val seeded_hash : int -> t -> int
724 A seeded hash function for strings, with the same output value as
726 Hashtbl.seeded_hash . This function allows this module to be passed as
727 argument to the functor Hashtbl.MakeSeeded .
728 Since 5.0.0
731 val get_int32_be : string -> int -> int32
735 get_int32_be b i is b 's big-endian 32-bit integer starting at charac‐
738 ter index i .
739 Since 4.13.0
742 val get_int32_le : string -> int -> int32
746 get_int32_le b i is b 's little-endian 32-bit integer starting at char‐
749 acter index i .
750 Since 4.13.0
753 val get_int64_ne : string -> int -> int64
757 get_int64_ne b i is b 's native-endian 64-bit integer starting at char‐
760 acter index i .
761 Since 4.13.0
764 val get_int64_be : string -> int -> int64
768 get_int64_be b i is b 's big-endian 64-bit integer starting at charac‐
771 ter index i .
772 Since 4.13.0
775 val get_int64_le : string -> int -> int64
779 get_int64_le b i is b 's little-endian 64-bit integer starting at char‐
782 acter index i .
783 Since 4.13.0
786OCamldoc 2023-07-20 Stdlib.String(3)