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Module CCStringSource

Basic String Utils

Sourcetype 'a iter = ('a -> unit) -> unit

Fast internal iterator.

  • since 2.8
Sourcetype 'a gen = unit -> 'a option

Documentation for the standard String module

include module type of struct include String end

Strings

Sourcetype t = string

The type for strings.

Sourceval make : int -> char -> string

make n c is a string of length n with each index holding the character c.

Sourceval init : int -> (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
Sourceval empty : string

The empty string.

  • since 4.13.0
Sourceval of_bytes : bytes -> string

Return a new string that contains the same bytes as the given byte sequence.

  • since 4.13.0
Sourceval to_bytes : string -> bytes

Return a new byte sequence that contains the same bytes as the given string.

  • since 4.13.0
Sourceval get : string -> int -> char

get s i is the character at index i in s. This is the same as writing s.[i].

Concatenating

Note. The Stdlib.(^) binary operator concatenates two strings.

Sourceval concat : string -> string list -> string

concat sep ss concatenates the list of strings ss, inserting the separator string sep between each.

Sourceval cat : string -> string -> string

cat s1 s2 concatenates s1 and s2 (s1 ^ s2).

  • since 4.13.0

Predicates and comparisons

Sourceval equal : t -> t -> bool

equal s0 s1 is true if and only if s0 and s1 are character-wise equal.

  • since 4.03.0 (4.05.0 in StringLabels)
Sourceval starts_with : prefix:string -> string -> bool

starts_with ~prefix s is true if and only if s starts with prefix.

  • since 4.13.0
Sourceval ends_with : suffix:string -> string -> bool

ends_with ~suffix s is true if and only if s ends with suffix.

  • since 4.13.0
Sourceval contains_from : string -> int -> char -> bool

contains_from s start c is true if and only if c appears in s after position start.

Sourceval 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.

Sourceval contains : string -> char -> bool

contains s c is String.contains_from s 0 c.

Extracting substrings

Sourceval sub : string -> int -> 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.

Transforming

Sourceval map : (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
Sourceval mapi : (int -> char -> char) -> string -> string

mapi f s is like map but the index of the character is also passed to f.

  • since 4.02.0
Sourceval fold_left : ('a -> char -> 'a) -> '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
Sourceval fold_right : (char -> 'a -> 'a) -> string -> '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
Sourceval 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
Sourceval 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).

Sourceval uppercase_ascii : string -> string

uppercase_ascii s is s with all lowercase letters translated to uppercase, using the US-ASCII character set.

  • since 4.03.0 (4.05.0 in StringLabels)
Sourceval lowercase_ascii : string -> string

lowercase_ascii s is s with all uppercase letters translated to lowercase, using the US-ASCII character set.

  • since 4.03.0 (4.05.0 in StringLabels)
Sourceval capitalize_ascii : string -> string

capitalize_ascii s is s with the first character set to uppercase, using the US-ASCII character set.

  • since 4.03.0 (4.05.0 in StringLabels)
Sourceval uncapitalize_ascii : string -> string

uncapitalize_ascii s is s with the first character set to lowercase, using the US-ASCII character set.

  • since 4.03.0 (4.05.0 in StringLabels)

Traversing

Sourceval iteri : (int -> char -> unit) -> string -> unit

iteri is like iter, but the function is also given the corresponding character index.

  • since 4.00.0

Searching

Sourceval 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

    if c does not occur in s after position i.

Sourceval 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
Sourceval 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

    if c does not occur in s before position i+1.

Sourceval 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
Sourceval index : string -> char -> int

index s c is String.index_from s 0 c.

Sourceval index_opt : string -> char -> int option

index_opt s c is String.index_from_opt s 0 c.

  • since 4.05
Sourceval rindex : string -> char -> int

rindex s c is String.rindex_from s (length s - 1) c.

Sourceval 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

Sourceval to_seqi : t -> (int * char) Seq.t

to_seqi s is like to_seq but also tuples the corresponding index.

  • since 4.07

UTF decoding and validations

  • since 4.14

UTF-8

Sourceval get_utf_8_uchar : t -> int -> Uchar.utf_decode

get_utf_8_uchar b i decodes an UTF-8 character at index i in b.

Sourceval is_valid_utf_8 : t -> bool

is_valid_utf_8 b is true if and only if b contains valid UTF-8 data.

UTF-16BE

Sourceval get_utf_16be_uchar : t -> int -> Uchar.utf_decode

get_utf_16be_uchar b i decodes an UTF-16BE character at index i in b.

Sourceval is_valid_utf_16be : t -> bool

is_valid_utf_16be b is true if and only if b contains valid UTF-16BE data.

UTF-16LE

Sourceval get_utf_16le_uchar : t -> int -> Uchar.utf_decode

get_utf_16le_uchar b i decodes an UTF-16LE character at index i in b.

Sourceval is_valid_utf_16le : t -> bool

is_valid_utf_16le b is true if and only if b contains valid UTF-16LE data.

Deprecated functions

Sourceval create : int -> bytes

create n returns a fresh byte sequence of length n. The sequence is uninitialized and contains arbitrary bytes.

Sourceval copy : string -> string

Return a copy of the given string.

  • deprecated

    Because strings are immutable, it doesn't make much sense to make identical copies of them.

Sourceval fill : bytes -> int -> int -> char -> unit

fill s pos len c modifies byte sequence s in place, replacing len bytes by c, starting at pos.

Sourceval 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.

  • deprecated

    Functions operating on Latin-1 character set are deprecated.

Sourceval 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.

  • deprecated

    Functions operating on Latin-1 character set are deprecated.

Sourceval 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..

  • deprecated

    Functions operating on Latin-1 character set are deprecated.

Sourceval 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.

  • deprecated

    Functions operating on Latin-1 character set are deprecated.

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.

Sourceval 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
Sourceval 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
Sourceval 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
Sourceval 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
Sourceval 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
Sourceval 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
Sourceval 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
Sourceval 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
Sourceval 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
Sourceval 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
Sourceval 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
Sourceval 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
Sourceval 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
Sourceval 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
Sourceval length : t -> int

Return the length (number of characters) of the given string.

Sourceval blit : t -> int -> Bytes.t -> int -> int -> unit

Like String.blit. Compatible with the -safe-string option.

Sourceval fold : ('a -> char -> 'a) -> 'a -> t -> 'a

Fold on chars by increasing index.

  • since 0.7

Conversions

Sourceval to_gen : t -> char gen

Return the gen of characters contained in the string.

Sourceval to_iter : t -> char iter

Return the iter of characters contained in the string.

  • since 2.8
Sourceval to_seq : t -> char Seq.t

to_seq s returns a Seq.t of the bytes in s. Renamed from to std_seq since 3.0.

  • since 3.0
Sourceval to_list : t -> char list

Return the list of characters contained in the string.

Sourceval pp_buf : Buffer.t -> t -> unit

Renamed from pp since 2.0.

Sourceval pp : Format.formatter -> t -> unit

Print the string within quotes.

Renamed from print since 2.0.

Sourceval compare : string -> string -> int
Sourceval is_empty : string -> bool

is_empty s returns true iff s is empty (i.e. its length is 0).

  • since 1.5
Sourceval hash : string -> int
Sourceval rev : string -> string

rev s returns the reverse of s.

  • since 0.17
Sourceval pad : ?side:[ `Left | `Right ] -> ?c:char -> int -> string -> string

pad n str ensures that str is at least n bytes long, and pads it on the side with c if it's not the case.

  • parameter side

    determines where padding occurs (default: `Left).

  • parameter c

    the char used to pad (default: ' ').

  • since 0.17
Sourceval of_char : char -> string

of_char 'a' is "a".

  • since 0.19
Sourceval of_gen : char gen -> string

Convert a gen of characters to a string.

Sourceval of_iter : char iter -> string

Convert a iter of characters to a string.

  • since 2.8
Sourceval of_seq : char Seq.t -> string

Convert a sequence of characters to a string. Renamed from of_std_seq since 3.0.

  • since 3.0
Sourceval of_list : char list -> string

Convert a list of characters to a string.

Sourceval of_array : char array -> string

Convert an array of characters to a string.

Sourceval to_array : string -> char array

Return the array of characters contained in the string.

Sourceval find : ?start:int -> sub:string -> string -> int

Find sub in string, returns its first index or -1.

Sourceval find_all : ?start:int -> sub:string -> string -> int gen

find_all ~sub s finds all occurrences of sub in s, even overlapping instances.

  • parameter start

    starting position in s.

  • since 0.17
Sourceval find_all_l : ?start:int -> sub:string -> string -> int list

find_all_l ~sub s finds all occurrences of sub in s and returns them in a list.

  • parameter start

    starting position in s.

  • since 0.17
Sourceval mem : ?start:int -> sub:string -> string -> bool

mem ~sub s is true iff sub is a substring of s.

  • since 0.12
Sourceval rfind : sub:string -> string -> int

Find sub in string from the right, returns its first index or -1. Should only be used with very small sub.

  • since 0.12
Sourceval replace : ?which:[ `Left | `Right | `All ] -> sub:string -> by:string -> string -> string

replace ~sub ~by s replaces some occurrences of sub by by in s.

  • parameter which

    decides whether the occurrences to replace are:

    • `Left first occurrence from the left (beginning).
    • `Right first occurrence from the right (end).
    • `All all occurrences (default).
  • since 0.14
Sourceval is_sub : sub:string -> int -> string -> int -> sub_len:int -> bool

is_sub ~sub i s j ~sub_len returns true iff the substring of sub starting at position i and of length sub_len is a substring of s starting at position j.

Sourceval repeat : string -> int -> string

The same string, repeated n times.

Sourceval prefix : pre:string -> string -> bool

prefix ~pre s returns true iff pre is a prefix of s.

Sourceval suffix : suf:string -> string -> bool

suffix ~suf s returns true iff suf is a suffix of s.

  • since 0.7
Sourceval chop_prefix : pre:string -> string -> string option

chop_prefix ~pre s removes pre from s if pre really is a prefix of s, returns None otherwise.

  • since 0.17
Sourceval chop_suffix : suf:string -> string -> string option

chop_suffix ~suf s removes suf from s if suf really is a suffix of s, returns None otherwise.

  • since 0.17
Sourceval take : int -> string -> string

take n s keeps only the n first chars of s.

  • since 0.17
Sourceval drop : int -> string -> string

drop n s removes the n first chars of s.

  • since 0.17
Sourceval take_drop : int -> string -> string * string

take_drop n s = take n s, drop n s.

  • since 0.17
Sourceval lines : string -> string list

lines s returns a list of the lines of s (splits along '\n').

  • since 0.10
Sourceval lines_gen : string -> string gen

lines_gen s returns a generator of the lines of s (splits along '\n').

  • since 0.10
Sourceval concat_gen : sep:string -> string gen -> string

concat_gen ~sep g concatenates all strings of g, separated with sep.

  • since 0.10
Sourceval unlines : string list -> string

unlines l concatenates all strings of l, separated with '\n'.

  • since 0.10
Sourceval unlines_gen : string gen -> string

unlines_gen g concatenates all strings of g, separated with '\n'.

  • since 0.10
Sourceval set : string -> int -> char -> string

set s i c creates a new string which is a copy of s, except for index i, which becomes c.

  • since 0.12
Sourceval iter : (char -> unit) -> string -> unit

Alias to String.iter.

  • since 0.12
Sourceval 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).

  • since 0.17
Sourceval filter : (char -> bool) -> string -> string

filter f s discards characters not satisfying f.

  • since 0.17
Sourceval flat_map : ?sep:string -> (char -> string) -> string -> string

Map each chars to a string, then concatenates them all.

  • parameter sep

    optional separator between each generated string.

  • since 0.12
Sourceval for_all : (char -> bool) -> string -> bool

True for all chars?

  • since 0.12
Sourceval exists : (char -> bool) -> string -> bool

True for some char?

  • since 0.12
Sourceval drop_while : (char -> bool) -> t -> t

drop_while f s discards any characters starting from the left, up to the first character c not satisfying f c.

  • since 2.2
Sourceval rdrop_while : (char -> bool) -> t -> t

rdrop_while f s discards any characters starting from the right, up to the first character c not satisfying f c.

  • since 2.2
Sourceval ltrim : t -> t

Trim space on the left (see String.trim for more details).

  • since 1.2
Sourceval rtrim : t -> t

Trim space on the right (see String.trim for more details).

  • since 1.2

Operations on 2 strings

Sourceval map2 : (char -> char -> char) -> string -> string -> string

Map pairs of chars.

  • since 0.12
Sourceval iter2 : (char -> char -> unit) -> string -> string -> unit

Iterate on pairs of chars.

  • since 0.12
Sourceval iteri2 : (int -> char -> char -> unit) -> string -> string -> unit

Iterate on pairs of chars with their index.

  • since 0.12
Sourceval fold2 : ('a -> char -> char -> 'a) -> 'a -> string -> string -> 'a

Fold on pairs of chars.

  • since 0.12
Sourceval for_all2 : (char -> char -> bool) -> string -> string -> bool

All pairs of chars respect the predicate?

  • since 0.12
Sourceval exists2 : (char -> char -> bool) -> string -> string -> bool

Exists a pair of chars?

  • since 0.12

Ascii functions

Those functions are deprecated in String since 4.03, so we provide a stable alias for them even in older versions.

Sourceval equal_caseless : string -> string -> bool

Comparison without respect to ascii lowercase.

  • since 1.2

Finding

A relatively efficient algorithm for finding sub-strings.

  • since 1.0
Sourcemodule Find : sig ... end

Splitting

Sourcemodule Split : sig ... end
Sourceval split_on_char : char -> string -> string list

Split the string along the given char.

  • since 1.2
Sourceval split : by:string -> string -> string list

Alias to Split.list_cpy.

  • since 1.2

Utils

Sourceval compare_versions : string -> string -> int

compare_versions a b compares version strings a and b, considering that numbers are above text.

  • since 0.13
Sourceval compare_natural : string -> string -> int

Natural Sort Order, comparing chunks of digits as natural numbers. https://en.wikipedia.org/wiki/Natural_sort_order

  • since 1.3
Sourceval edit_distance : ?cutoff:int -> string -> string -> int

Edition distance between two strings. This satisfies the classical distance axioms: it is always positive, symmetric, and satisfies the formula distance a b + distance b c >= distance a c.

  • parameter cutoff

    if provided, it's a cap on both the number of iterations, and on the result. (since 3.0). This is useful if you just want to check whether the edit distance is less or equal than 2 (use cutoff of 3).

Infix operators

  • since 3.0
Sourcemodule Infix : sig ... end
include module type of Infix
Sourceval (=) : t -> t -> bool
  • since 3.0
Sourceval (<>) : t -> t -> bool
  • since 3.0
Sourceval (<) : t -> t -> bool
  • since 3.0
Sourceval (<=) : t -> t -> bool
  • since 3.0
Sourceval (>=) : t -> t -> bool
  • since 3.0
Sourceval (>) : t -> t -> bool
  • since 3.0
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