wctob function — Converts a wide character to a single byte
int wctob(wint_t wc)
If the wide character wc has a single-byte representation as a multibyte character, wctob returns that byte; otherwise, it returns EOF.
wc
wctob
EOF
btowc function, EOF in <cstdio> , codecvt in <locale>
<cstdio>
codecvt
<locale>