mbtowc
extern int mbtowc(wchar_t *pwc, const char *string, size_t maxSize);
mbtowc(NULL, NULL, 0);
cnt = mbtowc(&wc, ins + i, ins_size - i);
int l = mbtowc(&wc2, p+1, 4);
int l = mbtowc(&wc, p, 4);
int k = mbtowc(&wc, str, n);
int k = mbtowc(&wc, pat, m);
B_DEFINE_WEAK_ALIAS(__mbtowc, mbtowc);
iret = mbtowc (&wc, s, n);
if ((r = mbtowc(&wc, &c, MB_CUR_MAX)) <= 0) {