/* 
  Program: robust.c

  Query the user for a positive integer.

*/

#include <stdio.h>
#include "genlib.h"
#include "simpio.h"

main() {
    int n, dsum;

    printf("Sum the digits in an integer.\n");

    while (TRUE) {
      printf("Enter a positive integer: ");
      n = GetInteger();
      if (n > 0) break ;
      printf("Positive integers only, please.\n");
    }

    dsum = 0;
    while (n > 0) {
        dsum += n % 10;
        n /= 10;
    }
    printf("The sum of the digits is %d\n", dsum);
}