/* program provides a framework for studying simple loop invariants
   the basic problem is to read a sequene of positive values
   and compute their average
*/

#include <stdio.h>

int main () {
  int count;
  double value;
  double sum;
        
  /* approach 1 */
  printf ( "First Approach\n");
  sum = 0.0;
  count = 0;
        
  printf ("Enter numbers (conclude with 0)\n");
  scanf ("%lf", &value);

  while (value > 0) {
    sum = sum + value;
    count = count + 1;
    scanf ("%lf", &value);
  }
  printf ("average = %6.2lf\n", sum/count);
        
  /* approach 2 */
  printf ("Second Approach\n");
  sum = 0.0;
  count = 0;
        
  printf ("Enter numbers (conclude with 0)\n");
  scanf ("%lf", &value);

  while (value > 0) {
   scanf ("%lf", &value);
   sum = sum + value;
   count = count + 1;
  }
  printf ("average = %6.2lf\n", sum/count);

  /* approach 3 */
  printf ("Third Approach\n");
  sum = 0.0;
  count = 0;
  value = 3.141592;

  printf ("Enter numbers (conclude with 0)\n");
  while (value > 0) {
   scanf ("%lf", &value);
    if (value > 0) {
      sum = sum + value;
      count = count + 1;
    }
  }
  printf ("average = %6.2lf\n", sum/count);

  /* approach 4 */
  printf ("Fourth Approach\n");
  sum = 0.0;
  count = 0;

  printf ("Enter numbers (conclude with 0)\n");
  do {
    scanf ("%lf", &value);
    if (value > 0) {
      sum = sum + value;
      count = count + 1;
    }
  }
  while (value > 0);

  printf ("average = %6.2lf\n", sum/count);

  /* approach 5 */
  printf ("Fifth Approach\n");
  sum = 0.0;
  count = 0;
  
  printf ("Enter numbers (conclude with 0)\n");
  do {
    scanf ("%lf", &value);
    sum = sum + value;
    count = count + 1;
  }
  while (value > 0);
  printf ("average = %6.2lf\n", sum/count);

} // end main