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### 2.45 `wctomb`—minimal wide char to multibyte converter

Synopsis

         #include <stdlib.h>
         int wctomb(char *s, wchar_t wchar);

Description
When _MB_CAPABLE is not defined, this is a minimal ANSI-conforming implementation of `wctomb`. The only “wide characters” recognized are single bytes, and they are “converted” to themselves.

When _MB_CAPABLE is defined, this routine calls `_wctomb_r` to perform the conversion, passing a state variable to allow state dependent decoding. The result is based on the locale setting which may be restricted to a defined set of locales.

Each call to `wctomb` modifies `*`s unless s is a null pointer or _MB_CAPABLE is defined and wchar is invalid.

Returns
This implementation of `wctomb` returns `0` if s is `NULL`; it returns `-1` if _MB_CAPABLE is enabled and the wchar is not a valid multi-byte character, it returns `1` if _MB_CAPABLE is not defined or the wchar is in reality a single byte character, otherwise it returns the number of bytes in the multi-byte character.

Portability
`wctomb` is required in the ANSI C standard. However, the precise effects vary with the locale.

`wctomb` requires no supporting OS subroutines.