#include <wchar.h> int wcsncasecmp(const wchar_t *s1, const wchar_t *s2, size_t n);
The wcsncasecmp function is the wide-character equivalent of the strncasecmp 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, ignoring case differences (towupper, towlower).
The wcsncasecmp function returns zero if the wide-character strings at s1 and s2, truncated to at most length n, are equal except for case distinctions. It returns a positive integer if truncated s1 is greater than truncated s2, ignoring case. It returns a negative integer if truncated s1 is smaller than truncated s2, ignoring case.