9.4.4 ctype.h: character handling functions

   

DESCRIPTION

This header file provides implementations of the following standard character handling functions:

isascii

Tests if a character is in the range 0-127. This is not supplied in ISO C but exists on many systems.

isalnum

Tests if a character is alphanumeric.

isalpha

Tests if a character is alphabetic.

iscntrl

Tests if a character is a control character.

isdigit

Tests if a character is a decimal digit.

isgraph

Tests if a character is a printable non-space character.

islower

Tests if a character is a lowercase letter.

isprint

Tests if a character is a printable character, including space.

ispunct

Tests if a character is a punctuation mark.

isspace

Tests if a character is a whitespace character of any kind.

isupper

Tests if a character is a uppercase letter.

isxdigit

Tests if a character is a hexadecimal digit.

toascii

Converts an integer into a 7-bit ASCII character.

tolower

Converts a character to lowercase.

toupper

Converts a character to uppercase.

The implementations of these functions provided by the minimal C library are directly-coded inline functions, and do not reference any global data structures such as character type arrays. They do not support locales (see Section 9.3), and only recognize the basic 7-bit ASCII character set (all characters above 126 are considered to be control characters).