wcsncmp - compare two fixed-size wide-character strings
int wcsncmp(const wchar_t *s1, const wchar_t *s2, size_t n);
The wcsncmp() function is the wide-character equivalent of the strncmp(3) function. It compares the wide-character string pointed to by s1 and the wide-character string pointed to by s2, but at most n wide characters from each string. In each string, the comparison extends only up to the first occurrence of a null wide character (L\(aq\0\(aq), if any.
The wcsncmp() function returns zero if the wide-character strings at s1 and s2, truncated to at most length n, are equal. It returns an integer greater than zero if at the first differing position i (i < n), the corresponding wide-character s1[i] is greater than s2[i]. It returns an integer less than zero if at the first differing position i (i < n), the corresponding wide-character s1[i] is less than s2[i].
For an explanation of the terms used in this section, see attributes(7).
POSIX.1-2001, POSIX.1-2008, C99.