Wide-character to single-byte conversion.
Standard library (libc.a)
#include <stdio.h>
#include <wchar.h>int wctob (wint_t c);The wctob function determines whether c corresponds to a member of the extended character set whose character representation is a single byte when in the initial shift state.
The behavior of this function is affected by the LC_CTYPE category of the current locale.
The wctob function returns EOF if c does not correspond to a character with length one in the initial shift state. Otherwise, it returns the single-byte representation of that character.