WCTOB(3) Linux Programmer's Manual WCTOB(3)

wctob - try to represent a wide character as a single byte

#include <wchar.h>
int wctob(wint_t c);

The wctob() function tests whether the multibyte representation of the wide character c, starting in the initial state, consists of a single byte. If so, it is returned as an unsigned char.
Never use this function. It cannot help you in writing internationalized programs. Internationalized programs must never distinguish single-byte and multibyte characters.

The wctob() function returns the single-byte representation of c, if it exists, of EOF otherwise.

For an explanation of the terms used in this section, see attributes(7).
Interface Attribute Value
wctob () Thread safety MT-Safe

POSIX.1-2001, POSIX.1-2008, C99.

The behavior of wctob() depends on the LC_CTYPE category of the current locale.
This function should never be used. Internationalized programs must never distinguish single-byte and multibyte characters. Use either wctomb(3) or the thread-safe wcrtomb(3) instead.

btowc(3), wcrtomb(3), wctomb(3)
2017-09-15 GNU