Example

       #include <string.h>
       #include <stdio.h>

       /* This program concatenates two strings using the strcat       */
       /* function, and then manually compares the result of strcat    */
       /* to the expected result.                                      */

       #define S1LENGTH 10
       #define S2LENGTH 8

       main()
       {
           static char s1buf[S1LENGTH + S2LENGTH] = "abcmnexyz";
           static char s2buf[] = " orthis";
           static char test1[] = "abcmnexyz orthis";

           int i;
           char *status;

           /* Take static buffer s1buf, concatenate static buffer      */
           /* s2buf to it, and compare the answer in s1buf with the    */
           /* static answer in test1.                                  */

           status = strcat(s1buf, s2buf);
           for (i = 0; i <= S1LENGTH + S2LENGTH - 2; i++) {
               /* Check for correct returned string.   */

               if (test1[i] != s1buf[i])
                   printf("error in strcat");
           }
       }