rem: mbtowc(pwc, s, n) int *pwc; const char *s; size_t n;
add: mbtowc(wchar_t *pwc, const char *s, size_t n)
context: mbtowc(pwc, s, n)	int *pwc;	const char *s;	size_t n;{	if (s == NULL)		return 0;	if (n == 0)		return -1;	if (pwc)		*pwc = (int) *s;	return (*s != '\0');}