1Stdlib.StringLabels(3) OCaml library Stdlib.StringLabels(3)
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6 Stdlib.StringLabels - no description
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9 Module Stdlib.StringLabels
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12 Module StringLabels
13 : (module Stdlib__StringLabels)
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21
22
23 Strings
24 type t = string
25
26
27 The type for strings.
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29
30
31 val make : int -> char -> string
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33
34 make n c is a string of length n with each index holding the character
35 c .
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37
38 Raises Invalid_argument if n < 0 or n > Sys.max_string_length .
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40
41
42 val init : int -> f:(int -> char) -> string
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44
45 init n ~f is a string of length n with index i holding the character f
46 i (called in increasing index order).
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48
49 Since 4.02.0
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51
52 Raises Invalid_argument if n < 0 or n > Sys.max_string_length .
53
54
55
56 val empty : string
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58 The empty string.
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60
61 Since 4.13.0
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63
64
65 val of_bytes : bytes -> string
66
67 Return a new string that contains the same bytes as the given byte se‐
68 quence.
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70
71 Since 4.13.0
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73
74
75 val to_bytes : string -> bytes
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77 Return a new byte sequence that contains the same bytes as the given
78 string.
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80
81 Since 4.13.0
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83
84
85 val length : string -> int
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88 length s is the length (number of bytes/characters) of s .
89
90
91
92 val get : string -> int -> char
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94
95 get s i is the character at index i in s . This is the same as writing
96 s.[i] .
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98
99 Raises Invalid_argument if i not an index of s .
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101
102
103
104 Concatenating
105 Note. The (^) binary operator concatenates two strings.
106
107 val concat : sep:string -> string list -> string
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110 concat ~sep ss concatenates the list of strings ss , inserting the sep‐
111 arator string sep between each.
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114 Raises Invalid_argument if the result is longer than
115 Sys.max_string_length bytes.
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117
118
119 val cat : string -> string -> string
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121
122 cat s1 s2 concatenates s1 and s2 ( s1 ^ s2 ).
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124
125 Since 4.13.0
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128 Raises Invalid_argument if the result is longer than
129 Sys.max_string_length bytes.
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132
133
134 Predicates and comparisons
135 val equal : t -> t -> bool
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137
138 equal s0 s1 is true if and only if s0 and s1 are character-wise equal.
139
140
141 Since 4.05.0
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145 val compare : t -> t -> int
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148 compare s0 s1 sorts s0 and s1 in lexicographical order. compare be‐
149 haves like compare on strings but may be more efficient.
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152
153 val starts_with : prefix:string -> string -> bool
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155
156 starts_with ~prefix s is true if and only if s starts with prefix .
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159 Since 4.13.0
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163 val ends_with : suffix:string -> string -> bool
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166 ends_with ~suffix s is true if and only if s ends with suffix .
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169 Since 4.13.0
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172
173 val contains_from : string -> int -> char -> bool
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176 contains_from s start c is true if and only if c appears in s after po‐
177 sition start .
178
179
180 Raises Invalid_argument if start is not a valid position in s .
181
182
183
184 val rcontains_from : string -> int -> char -> bool
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187 rcontains_from s stop c is true if and only if c appears in s before
188 position stop+1 .
189
190
191 Raises Invalid_argument if stop < 0 or stop+1 is not a valid position
192 in s .
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194
195
196 val contains : string -> char -> bool
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199 contains s c is String.contains_from s 0 c .
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201
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204 Extracting substrings
205 val sub : string -> pos:int -> len:int -> string
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207
208 sub s ~pos ~len is a string of length len , containing the substring of
209 s that starts at position pos and has length len .
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211
212 Raises Invalid_argument if pos and len do not designate a valid sub‐
213 string of s .
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215
216
217 val split_on_char : sep:char -> string -> string list
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220 split_on_char ~sep s is the list of all (possibly empty) substrings of
221 s that are delimited by the character sep .
222
223 The function's result is specified by the following invariants:
224
225 -The list is not empty.
226
227 -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
231 -No string in the result contains the sep character.
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235 Since 4.05.0
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240 Transforming
241 val map : f:(char -> char) -> string -> string
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244 map f s is the string resulting from applying f to all the characters
245 of s in increasing order.
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248 Since 4.00.0
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250
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252 val mapi : f:(int -> char -> char) -> string -> string
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255 mapi ~f s is like StringLabels.map but the index of the character is
256 also passed to f .
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259 Since 4.02.0
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262
263 val fold_left : f:('a -> char -> 'a) -> init:'a -> string -> 'a
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266 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 .
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270 Since 4.13.0
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274 val fold_right : f:(char -> 'a -> 'a) -> string -> init:'a -> 'a
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277 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 .
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281 Since 4.13.0
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285 val for_all : f:(char -> bool) -> string -> bool
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287
288 for_all p s checks if all characters in s satisfy the predicate p .
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291 Since 4.13.0
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295 val exists : f:(char -> bool) -> string -> bool
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298 exists p s checks if at least one character of s satisfies the predi‐
299 cate p .
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302 Since 4.13.0
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306 val trim : string -> string
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309 trim s is s without leading and trailing whitespace. Whitespace charac‐
310 ters are: ' ' , '\x0C' (form feed), '\n' , '\r' , and '\t' .
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313 Since 4.00.0
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317 val escaped : string -> string
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320 escaped s is s with special characters represented by escape sequences,
321 following the lexical conventions of OCaml.
322
323 All characters outside the US-ASCII printable range [0x20;0x7E] are es‐
324 caped, as well as backslash (0x2F) and double-quote (0x22).
325
326 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
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331 Raises Invalid_argument if the result is longer than
332 Sys.max_string_length bytes.
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335
336 val uppercase_ascii : string -> string
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339 uppercase_ascii s is s with all lowercase letters translated to upper‐
340 case, using the US-ASCII character set.
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343 Since 4.05.0
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347 val lowercase_ascii : string -> string
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350 lowercase_ascii s is s with all uppercase letters translated to lower‐
351 case, using the US-ASCII character set.
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354 Since 4.05.0
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358 val capitalize_ascii : string -> string
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361 capitalize_ascii s is s with the first character set to uppercase, us‐
362 ing the US-ASCII character set.
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365 Since 4.05.0
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369 val uncapitalize_ascii : string -> string
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372 uncapitalize_ascii s is s with the first character set to lowercase,
373 using the US-ASCII character set.
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376 Since 4.05.0
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381 Traversing
382 val iter : f:(char -> unit) -> string -> unit
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385 iter ~f s applies function f in turn to all the characters of s . It
386 is equivalent to f s.[0]; f s.[1]; ...; f s.[length s - 1]; () .
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389
390 val iteri : f:(int -> char -> unit) -> string -> unit
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393 iteri is like StringLabels.iter , but the function is also given the
394 corresponding character index.
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397 Since 4.00.0
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402 Searching
403 val index_from : string -> int -> char -> int
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406 index_from s i c is the index of the first occurrence of c in s after
407 position i .
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410 Raises Not_found if c does not occur in s after position i .
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413 Raises Invalid_argument if i is not a valid position in s .
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417 val index_from_opt : string -> int -> char -> int option
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420 index_from_opt s i c is the index of the first occurrence of c in s af‐
421 ter position i (if any).
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424 Since 4.05
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427 Raises Invalid_argument if i is not a valid position in s .
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431 val rindex_from : string -> int -> char -> int
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434 rindex_from s i c is the index of the last occurrence of c in s before
435 position i+1 .
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438 Raises Not_found if c does not occur in s before position i+1 .
439
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441 Raises Invalid_argument if i+1 is not a valid position in s .
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445 val rindex_from_opt : string -> int -> char -> int option
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448 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).
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452 Since 4.05
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455 Raises Invalid_argument if i+1 is not a valid position in s .
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459 val index : string -> char -> int
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462 index s c is String.index_from s 0 c .
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466 val index_opt : string -> char -> int option
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469 index_opt s c is String.index_from_opt s 0 c .
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472 Since 4.05
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476 val rindex : string -> char -> int
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479 rindex s c is String.rindex_from s (length s - 1) c .
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483 val rindex_opt : string -> char -> int option
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486 rindex_opt s c is String.rindex_from_opt s (length s - 1) c .
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489 Since 4.05
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494 Strings and Sequences
495 val to_seq : t -> char Seq.t
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497
498 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.
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503 Since 4.07
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507 val to_seqi : t -> (int * char) Seq.t
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510 to_seqi s is like StringLabels.to_seq but also tuples the corresponding
511 index.
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514 Since 4.07
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518 val of_seq : char Seq.t -> t
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520
521 of_seq s is a string made of the sequence's characters.
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524 Since 4.07
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529 UTF decoding and validations
530 UTF-8
531 val get_utf_8_uchar : t -> int -> Uchar.utf_decode
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534 get_utf_8_uchar b i decodes an UTF-8 character at index i in b .
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537
538 val is_valid_utf_8 : t -> bool
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541 is_valid_utf_8 b is true if and only if b contains valid UTF-8 data.
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545
546 UTF-16BE
547 val get_utf_16be_uchar : t -> int -> Uchar.utf_decode
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550 get_utf_16be_uchar b i decodes an UTF-16BE character at index i in b .
551
552
553
554 val is_valid_utf_16be : t -> bool
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557 is_valid_utf_16be b is true if and only if b contains valid UTF-16BE
558 data.
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562
563 UTF-16LE
564 val get_utf_16le_uchar : t -> int -> Uchar.utf_decode
565
566
567 get_utf_16le_uchar b i decodes an UTF-16LE character at index i in b .
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569
570
571 val is_valid_utf_16le : t -> bool
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574 is_valid_utf_16le b is true if and only if b contains valid UTF-16LE
575 data.
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578
579 val blit : src:string -> src_pos:int -> dst:bytes -> dst_pos:int ->
580 len:int -> unit
581
582
583 blit ~src ~src_pos ~dst ~dst_pos ~len copies len bytes from the string
584 src , starting at index src_pos , to byte sequence dst , starting at
585 character number dst_pos .
586
587
588 Raises Invalid_argument if src_pos and len do not designate a valid
589 range of src , or if dst_pos and len do not designate a valid range of
590 dst .
591
592
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594
595 Binary decoding of integers
596 The functions in this section binary decode integers from strings.
597
598 All following functions raise Invalid_argument if the characters needed
599 at index i to decode the integer are not available.
600
601 Little-endian (resp. big-endian) encoding means that least (resp. most)
602 significant bytes are stored first. Big-endian is also known as net‐
603 work byte order. Native-endian encoding is either little-endian or
604 big-endian depending on Sys.big_endian .
605
606 32-bit and 64-bit integers are represented by the int32 and int64
607 types, which can be interpreted either as signed or unsigned numbers.
608
609 8-bit and 16-bit integers are represented by the int type, which has
610 more bits than the binary encoding. These extra bits are sign-extended
611 (or zero-extended) for functions which decode 8-bit or 16-bit integers
612 and represented them with int values.
613
614 val get_uint8 : string -> int -> int
615
616
617 get_uint8 b i is b 's unsigned 8-bit integer starting at character in‐
618 dex i .
619
620
621 Since 4.13.0
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623
624
625 val get_int8 : string -> int -> int
626
627
628 get_int8 b i is b 's signed 8-bit integer starting at character index i
629 .
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631
632 Since 4.13.0
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635
636 val get_uint16_ne : string -> int -> int
637
638
639 get_uint16_ne b i is b 's native-endian unsigned 16-bit integer start‐
640 ing at character index i .
641
642
643 Since 4.13.0
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645
646
647 val get_uint16_be : string -> int -> int
648
649
650 get_uint16_be b i is b 's big-endian unsigned 16-bit integer starting
651 at character index i .
652
653
654 Since 4.13.0
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656
657
658 val get_uint16_le : string -> int -> int
659
660
661 get_uint16_le b i is b 's little-endian unsigned 16-bit integer start‐
662 ing at character index i .
663
664
665 Since 4.13.0
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667
668
669 val get_int16_ne : string -> int -> int
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671
672 get_int16_ne b i is b 's native-endian signed 16-bit integer starting
673 at character index i .
674
675
676 Since 4.13.0
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678
679
680 val get_int16_be : string -> int -> int
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682
683 get_int16_be b i is b 's big-endian signed 16-bit integer starting at
684 character index i .
685
686
687 Since 4.13.0
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689
690
691 val get_int16_le : string -> int -> int
692
693
694 get_int16_le b i is b 's little-endian signed 16-bit integer starting
695 at character index i .
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697
698 Since 4.13.0
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700
701
702 val get_int32_ne : string -> int -> int32
703
704
705 get_int32_ne b i is b 's native-endian 32-bit integer starting at char‐
706 acter index i .
707
708
709 Since 4.13.0
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712
713 val hash : t -> int
714
715 An unseeded hash function for strings, with the same output value as
716 Hashtbl.hash . This function allows this module to be passed as argu‐
717 ment to the functor Hashtbl.Make .
718
719
720 Since 5.0.0
721
722
723
724 val seeded_hash : int -> t -> int
725
726 A seeded hash function for strings, with the same output value as
727 Hashtbl.seeded_hash . This function allows this module to be passed as
728 argument to the functor Hashtbl.MakeSeeded .
729
730
731 Since 5.0.0
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734
735 val get_int32_be : string -> int -> int32
736
737
738 get_int32_be b i is b 's big-endian 32-bit integer starting at charac‐
739 ter index i .
740
741
742 Since 4.13.0
743
744
745
746 val get_int32_le : string -> int -> int32
747
748
749 get_int32_le b i is b 's little-endian 32-bit integer starting at char‐
750 acter index i .
751
752
753 Since 4.13.0
754
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756
757 val get_int64_ne : string -> int -> int64
758
759
760 get_int64_ne b i is b 's native-endian 64-bit integer starting at char‐
761 acter index i .
762
763
764 Since 4.13.0
765
766
767
768 val get_int64_be : string -> int -> int64
769
770
771 get_int64_be b i is b 's big-endian 64-bit integer starting at charac‐
772 ter index i .
773
774
775 Since 4.13.0
776
777
778
779 val get_int64_le : string -> int -> int64
780
781
782 get_int64_le b i is b 's little-endian 64-bit integer starting at char‐
783 acter index i .
784
785
786 Since 4.13.0
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791
792OCamldoc 2023-07-20 Stdlib.StringLabels(3)