/* Sentinel controlled loop - BAD - explained */

#include <stdio.h>
#define SENTINEL -1

int main(void) {
  int sum, number;

  /* Initialization */
  sum = 0;

  do{
    /* Get number */
    printf("Enter number (-1 terminates): ");
    scanf("%d", &number);

    /* Add number to sum - SENTINEL is added to sum as well! */
    sum += number;

  } while (number != SENTINEL);

  /* Report the output */
  printf("The sum is %d\n", 
         sum);

  return 0;
}