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Module TableclothChar

Functions for working with single characters.

Character literals are enclosed in 'a' pair of single quotes.

let digit = '7'

The functions in this module work on ASCII characters (range 0-255) only, not Unicode.

Since character 128 through 255 have varying values depending on what standard you are using (ISO 8859-1 or Windows 1252), you are advised to stick to the 0-127 range.

type t​

type t = char

Create​

You can also create a Char using single quotes:

let char = 'c'

val fromCode​

val fromCode : int -> char option

Convert an ASCII code point to a character.

Returns None if the codepoint is outside the range of 0 to 255 inclusive.

Examples

Char.fromCode 65 = Some 'A'
Char.fromCode 66 = Some 'B'
Char.fromCode 3000 = None
Char.fromCode (-1) = None

The full range of extended ASCII is from 0 to 255. For numbers outside that range, you get None.

val from_code​

val from_code : int -> char option

val fromString​

val fromString : string -> char option

Converts a string to character. Returns None when the string isn't of length one.

Examples

Char.fromString "A" = Some 'A'
Char.fromString " " = Some ' '
Char.fromString "" = None
Char.fromString "abc" = None
Char.fromString " a" = None

val from_string​

val from_string : string -> char option

Query​

val isLowercase​

val isLowercase : char -> bool

Detect lower case ASCII characters.

Examples

Char.isLowercase 'a' = true
Char.isLowercase 'b' = true
Char.isLowercase 'z' = true
Char.isLowercase '0' = false
Char.isLowercase 'A' = false
Char.isLowercase '-' = false

val is_lowercase​

val is_lowercase : char -> bool

val isUppercase​

val isUppercase : char -> bool

Detect upper case ASCII characters.

Examples

Char.isUppercase 'A' = true
Char.isUppercase 'B' = true
Char.isUppercase 'Z' = true
Char.isUppercase 'h' = false
Char.isUppercase '0' = false
Char.isUppercase '-' = false

val is_uppercase​

val is_uppercase : char -> bool

val isLetter​

val isLetter : char -> bool

Detect upper and lower case ASCII alphabetic characters.

Examples

Char.isLetter 'a' = true
Char.isLetter 'b' = true
Char.isLetter 'E' = true
Char.isLetter 'Y' = true
Char.isLetter '0' = false
Char.isLetter '-' = false

val is_letter​

val is_letter : char -> bool

val isDigit​

val isDigit : char -> bool

Detect when a character is a number

Examples

Char.isDigit '0' = true
Char.isDigit '1' = true
Char.isDigit '9' = true
Char.isDigit 'a' = false
Char.isDigit 'b' = false

val is_digit​

val is_digit : char -> bool

val isAlphanumeric​

val isAlphanumeric : char -> bool

Detect upper case, lower case and digit ASCII characters.

Examples

Char.isAlphanumeric 'a' = true
Char.isAlphanumeric 'b' = true
Char.isAlphanumeric 'E' = true
Char.isAlphanumeric 'Y' = true
Char.isAlphanumeric '0' = true
Char.isAlphanumeric '7' = true
Char.isAlphanumeric '-' = false

val is_alphanumeric​

val is_alphanumeric : char -> bool

val isPrintable​

val isPrintable : char -> bool

Detect if a character is a printable character

A Printable character has a Char.toCode in the range 32 to 127, inclusive (' ' to '~').

Examples

Char.isPrintable 'G' = true
Char.isPrintable '%' = true
Char.isPrintable ' ' = true
Char.isPrintable '\t' = false
Char.isPrintable '\007' = false

val is_printable​

val is_printable : char -> bool

val isWhitespace​

val isWhitespace : char -> bool

Detect one of the following characters:

  • '\t' (tab)
  • '\n' (newline)
  • '\011' (vertical tab)
  • '\012' (form feed)
  • '\r' (carriage return)
  • ' ' (space)

Examples

Char.isWhitespace '\t' = true
Char.isWhitespace ' ' = true
Char.isWhitespace '?' = false
Char.isWhitespace 'G' = false

val is_whitespace​

val is_whitespace : char -> bool

Modify​

val toLowercase​

val toLowercase : char -> char

Converts an ASCII character to lower case, preserving non alphabetic ASCII characters.

Examples

Char.toLowercase 'A' = 'a'
Char.toLowercase 'B' = 'b'
Char.toLowercase '7' = '7'

val to_lowercase​

val to_lowercase : char -> char

val toUppercase​

val toUppercase : char -> char

Convert an ASCII character to upper case, preserving non alphabetic ASCII characters.

Examples

toUppercase 'a' = 'A'
toUppercase 'b' = 'B'
toUppercase '7' = '7'

val to_uppercase​

val to_uppercase : char -> char

Convert​

val toCode​

val toCode : char -> int

Convert to the corresponding ASCII code point``cp.

cp: https://en.wikipedia.org/wiki/Code_point

Examples

Char.toCode 'A' = 65
Char.toCode 'B' = 66

val to_code​

val to_code : char -> int

val toString​

val toString : char -> string

Convert a character into a string.

Examples

Char.toString 'A' = "A"
Char.toString '{' = "{"
Char.toString '7' = "7"

val to_string​

val to_string : char -> string

val toDigit​

val toDigit : char -> int option

Converts a digit character to its corresponding Int.

Returns None when the character isn't a digit.

Examples

Char.toDigit "7" = Some 7
Char.toDigit "0" = Some 0
Char.toDigit "A" = None
Char.toDigit "" = None

val to_digit​

val to_digit : char -> int option

Compare​

val equal​

val equal : t -> t -> bool

Test two Chars for equality

val compare​

val compare : t -> t -> int

Compare two Chars

type identity​

type identity

The unique identity for Comparator

val comparator​

val comparator : ( t, identity ) TableclothComparator.t