strxfrm
Syntax:
  #include <string.h>
  size_t strxfrm( char *str1, const char *str2, size_t num );

The strxfrm() function manipulates the first num characters of str2 and stores them in str1. The result is such that if a strcoll() is performed on str1 and the old str2, you will get the same result as with a strcmp().