Figure 6.9  Function scan_fraction (incomplete)
/*
 * Gets and returns a valid fraction as its result
 * A valid fraction is of this form: integer/positive integer
 * Pre : none
 */
void
scan_fraction(int *nump, int *denomp)
{
      char slash;    /* character between numerator and denominator 	*/
      int  status;   /* status code returned by scanf indicating number of valid values obtained	*/
      int  error;    /* flag indicating presence of an error 	*/
      char discard;  /* unprocessed character from input line 	*/

      do {
          /* No errors detected yet 	*/
          error = 0;

          /* Get a fraction from the user 	*/
          printf("Enter a common fraction as two integers separated ");
          printf("by a slash> ");

	       status = scanf("%d %c%d",_______, _______, _______);

          /* Validate the fraction 	*/
          if (status < 3) {
                error = 1;
                printf("Invalid-please read directions carefully\n"); 
          } else if (slash != '/') {
                error = 1;
                printf("Invalid-separate numerator and denominator");
                printf(" by a slash (/)\n");
          } else if (*denomp <= 0) {
                error = 1;
                printf("Invalid-denominator must be positive\n");
          }

          /* Discard extra input characters 	*/
          do {
              scanf("%c", &discard);
          } while (discard != '\n');
      } while (error);
}