ISASCII(3) Library Functions Manual ISASCII(3)

isascii
test for ASCII character

Standard C Library (libc, -lc)

#include <ctype.h>

int
isascii(int c);

The isascii() function tests for an ASCII character, which is any character with a value in the range from 0 to 127, inclusive.

The isascii() is defined on all integer values.

ctype(3), isalnum(3), isalpha(3), isblank(3), iscntrl(3), isdigit(3), isgraph(3), islower(3), isprint(3), ispunct(3), isspace(3), isupper(3), isxdigit(3), stdio(3), toascii(3), tolower(3), toupper(3), ascii(7)

The isascii() function conforms to X/Open Portability Guide Issue 4 (“XPG4”) and IEEE Std 1003.1-2001 (“POSIX.1”). The IEEE Std 1003.1-2008 (“POSIX.1”) revision however marked it as obsolete, noting that isascii() cannot be used portably in a localized application.
April 30, 2010 NetBSD 9.2