The wctob function tests whether the multi-byte 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 multi-byte characters.
The wctob function returns the single-byte representation of c, if it exists, of EOF otherwise.
ISO/ANSI C, UNIX98