c/string/multibyte/wctob

Narrows a wide character if its multibyte character equivalent in the initial shift state is a single byte.

This is typically possible for the characters from the ASCII character set, since most multibyte encodings (such as UTF-8) use single bytes to encode those characters.

Return value
eof if does not represent a multibyte character with length  in initial shift state.

otherwise, the single-byte representation of as  converted to