isascii
POSIX specification:
http://www.opengroup.org/onlinepubs/9699919799/functions/isascii.html
Gnulib module: —
Portability problems fixed by Gnulib:
Portability problems not fixed by Gnulib:
Note: This function's behaviour depends on the locale, but requires special
handling for the multibyte characters that occur in strings in locales with
MB_CUR_MAX > 1
(this includes all the common UTF-8 locales).
There are two alternative APIs:
c_isascii
mb_isascii