program4_06.c

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/* Program 4.6 The almost indefinite loop - computing an average */
#include <stdio.h>
#include <ctype.h>           /* For tolower() function */

int main(void)
{
  char answer = 'N';        /* Records yes or no to continue the loop */
  double total = 0.0;       /* Total of values entered                */
  double value = 0.0;       /* Value entered                          */
  int count = 0;            /* Number of values entered               */

  printf("\nThis program calculates the average of"
                                       " any number of values.");

  for( ;; )                           /* Indefinite loop */
  {
    printf ("\nEnter a value: ");     /* Prompt for the next value */
    scanf(" %lf", &value);            /* Read the next value       */
    total += value;                   /* Add value to total        */
    ++count;                          /* Increment count of values */

    /* check for more input */
    printf("Do you want to enter another value? (Y or N): ");
    scanf(" %c", &answer );           /* Read response Y or N   */

    if( tolower(answer) == 'n' )     /* look for any sign of no */
      break;                         /* Exit from the loop      */
  }
  /* output the average to 2 decimal places */
  printf ("\nThe average is %.2lf\n", total/count );
  return 0;
}