3.3 isascii, isascii_l—ASCII character predicate

Synopsis

#include <ctype.h>
int isascii(int c);

#include <ctype.h>
int isascii_l(int c, locale_t locale);

Description
isascii is a macro which returns non-zero when c is an ASCII character, and 0 otherwise. It is defined for all integer values.

isascii_l is like isascii but performs the check based on the locale specified by the locale object locale. If locale is LC_GLOBAL_LOCALE or not a valid locale object, the behaviour is undefined.

You can use a compiled subroutine instead of the macro definition by undefining the macro using ‘#undef isascii’ or ‘#undef isascii_l’.

Returns
isascii, isascii_l return non-zero if the low order byte of c is in the range 0 to 127 (0x00–0x7F).

Portability
isascii is ANSI C. isascii_l is a GNU extension.

No supporting OS subroutines are required.