#include <wchar.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <locale.h>

  /* This program verifies that two transformed strings,    */
  /* when passed through wcsxfrm and then compared, provide */
  /* the same result as if passed through wcscoll without   */
  /* any transformation.                                    */

 #define  BUFF_SIZE  20

 main()
 {
     wchar_t w_string1[BUFF_SIZE];
     wchar_t w_string2[BUFF_SIZE];
     wchar_t w_string3[BUFF_SIZE];
     wchar_t w_string4[BUFF_SIZE];
     int errno;
     int coll_result;
     int wcscmp_result;
     size_t wcsxfrm_result1;
     size_t wcsxfrm_result2;

     /* setlocale to French locale */

     if (setlocale(LC_ALL, "fr_FR.ISO8859-1") == NULL) {
         perror("setlocale");
         exit(EXIT_FAILURE);
     }

     /* Convert each of the strings into wide-character format. */

     if (mbstowcs(w_string1, "<a`>bcd", BUFF_SIZE) == (size_t)-1) {

         perror("mbstowcs");
         exit(EXIT_FAILURE);
     }

     if (mbstowcs(w_string2, "abcz", BUFF_SIZE) == (size_t)-1) {

         perror("mbstowcs");
         exit(EXIT_FAILURE);
     }

     /* Collate string 1 and string 2 and store the result. */

     errno = 0;
     coll_result = wcscoll(w_string1, w_string2);
     if (errno) {
         perror("wcscoll");
         exit(EXIT_FAILURE);
     }
     else {

        /*  Transform the strings (using wcsxfrm) into  */
        /*  w_string3 and w_string4.                    */

        wcsxfrm_result1 = wcsxfrm(w_string3, w_string1, BUFF_SIZE);

        if (wcsxfrm_result1 == ((size_t) - 1))
            perror("wcsxfrm");
        else if (wcsxfrm_result1 > BUFF_SIZE) {
            perror("\n** String is too long **\n");
            exit(EXIT_FAILURE);
        }
        else {
           wcsxfrm_result2 = wcsxfrm(w_string4, w_string2, BUFF_SIZE);
           if (wcsxfrm_result2 == ((size_t) - 1)) {
               perror("wcsxfrm");
               exit(EXIT_FAILURE);
            }
           else if (wcsxfrm_result2 > BUFF_SIZE) {
               perror("\n** String is too long **\n");
               exit(EXIT_FAILURE);
            }

         /* Compare the two transformed strings and verify that  */
         /* the result is the same as the result from wcscoll on */
         /* the original strings.                                */

           else {
               wcscmp_result = wcscmp(w_string3, w_string4);
               if (wcscmp_result == 0 && (coll_result == 0)) {
                   printf("\nReturn value from wcscoll() and return value"
                                        " from wcscmp() are both zero.");
                   printf("\nThe program was successful\n\n");
               }
               else if ((wcscmp_result < 0) && (coll_result < 0)) {
                   printf("\nReturn value from wcscoll() and return value"
                                   " from wcscmp() are less than zero.");
                   printf("\nThe program was successful\n\n");
               }
               else if ((wcscmp_result > 0) && (coll_result > 0)) {
                   printf("\nReturn value from wcscoll() and return value"
                                 " from wcscmp() are greater than zero.");
                   printf("\nThe program was successful\n\n");
               }
               else {
                   printf("** Error **\n");
                   printf("\nReturn values are not of the same type");
               }
            }
        }
     }
 }

    Running the example program produces the following result:

    Return value from wcscoll() and return value
           from wcscmp() are less than zero.
    The program was successful