size_t wcstombs(char *str
const wchar_t *pwcs
Converts the codes stored in the array pwcs to multibyte
characters and stores them in the string str. It copies
at most n bytes to the string. If a multibyte character
overflows the n constriction, then none of that multibyte
character's bytes are copied. Conversion stops when it reaches
the null character or n bytes have been written to the
string. The null character is stored in the string, but is not
counted in the return value.
If an invalid code is reached, the value -1 is returned.
Otherwise the number of bytes stored in the string is returned
not including the terminating null character.