Char

Classifying and converting characters (ASCII), like System.Char in C#:

if (Char.IsDigit(c))
    value = value * 10 + (c - '0');

A char is a byte of UTF-8 text: the functions only know the ASCII characters; every byte above 127 is neither a letter nor a digit.

Functions

Name	Description
`IsDigit`	Whether `c` is a decimal digit (`0` to `9`).
`IsUpper`	Whether `c` is an uppercase ASCII letter (`A` to `Z`).
`IsLower`	Whether `c` is a lowercase ASCII letter (`a` to `z`).
`IsLetter`	Whether `c` is an ASCII letter.
`IsLetterOrDigit`	Whether `c` is an ASCII letter or a decimal digit.
`IsHexDigit`	Whether `c` is a hexadecimal digit (`0` to `9`, `a` to `f`, `A` to `F`).
`IsWhiteSpace`	Whether `c` is white space: a space, a tab, a line break (`\n`, `\r`), a vertical tab or a form feed.
`ToUpper`	`c` as an uppercase letter; any other character stays as it is.
`ToLower`	`c` as a lowercase letter; any other character stays as it is.
`HexValue`	The value of a hexadecimal digit (0 to 15).

bool IsDigit(char c)

Whether c is a decimal digit (0 to 9).

bool IsUpper(char c)

Whether c is an uppercase ASCII letter (A to Z).

bool IsLower(char c)

Whether c is a lowercase ASCII letter (a to z).

bool IsLetter(char c)

Whether c is an ASCII letter.

bool IsLetterOrDigit(char c)

Whether c is an ASCII letter or a decimal digit.

bool IsHexDigit(char c)

Whether c is a hexadecimal digit (0 to 9, a to f, A to F).

bool IsWhiteSpace(char c)

Whether c is white space: a space, a tab, a line break (\n, \r), a vertical tab or a form feed.

char ToUpper(char c)

c as an uppercase letter; any other character stays as it is.

char ToLower(char c)

c as a lowercase letter; any other character stays as it is.

int HexValue(char c)

The value of a hexadecimal digit (0 to 15).

Returns -1 if c is not a hexadecimal digit.