int wcsncmp(const wchar_t *s1, const wchar_t *s2, size_t n);
wcsncmp compares not more than n wide characters from the array pointed to by s1 to the array pointed to by s2. Characters that follow a null wide character are not compared.
wcsncmp returns an integer greater than, equal to, or less than zero, if the possibly null-terminated array pointed to by s1 is greater than, equal to, or less than the possibly null-terminated array pointed to by s2.