mbtowc() in System Libraries STDLIB

IMPORT_C int mbtowc(wchar_t *pwc, const char *s, size_t n);

Converts the multibyte character addressed by s into the corresponding UNICODE character pwc

`wchar_t *pwc`	Is the address of a wide character, type wchar_t, to receive the UNICODE equivalent of s.
`const char *s`	Points to the multibyte character to be converted to UNICODE.
`size_t n`	Is the maximum width, in bytes, for which to scan s for a valid multibyte sequence. Regardless of the value of n, no more than MB_CUR_MAX bytes are examined.

int

the length, in bytes, of the multibyte character for which it found a UNICODE equivalent