Description

   The strings are compared until a null character is encountered,
   the strings differ, or maxchar is reached. If characters differ,
   wcsncmp returns:

   o  An integer less than 0 if the codepoint of the first differing
      character in wstr_1 is less than the codepoint of the
      corresponding character in wstr_2

   o  An integer greater than 0 if the codepoint of the first
      differing character in wstr_1 is greater than the codepoint
      of the corresponding character in wstr_2

   If no differences are found after comparing maxchar characters,
   the function returns 0.

   See also wcscmp.