CSC133 Intro to CS in C++: Loop Example

Sample Program: Event Controlled Loop

//  This program calculates the average of a set of exams.
//  The user is prompted to enter the exam scores and to enter -99
//  when there are no more scores. The average will be printed.

#include <iostream.h>
#include <iomanip.h>

int main()
{
   const int SENTINEL = -99;
   int grade;
   int numberOfGrades;
   int totalGrades;
   float averageGrade;

//  initialize the total and number of grades read in
   totalGrades = 0;
   numberOfGrades = 0;

//  read in the grades, total them, and count how many grades there are
   cout << "Enter the first exam score (enter -99 to end): ";
   cin >> grade;
   while (grade != SENTINEL)
   {
      totalGrades = totalGrades + grade;
      numberOfGrades = numberOfGrades + 1;
      cout << "Enter the next exam score (enter -99 to end): ";
      cin >> grade;
   }

//  calculate and print the average
   averageGrade = float(totalGrades) / numberOfGrades;
   cout << setiosflags(ios::fixed);
   cout << setiosflags(ios::showpoint);
   cout << setprecision(1);
   cout << "The average grade for the exam is :  " << averageGrade << endl;
}

Sample Execution:

Enter the first exam score (enter -99 to end): 95
Enter the next exam score (enter -99 to end): 85
Enter the next exam score (enter -99 to end): 75
Enter the next exam score (enter -99 to end): 90
Enter the next exam score (enter -99 to end): 80
Enter the next exam score (enter -99 to end): -99
The average grade for the exam is :  85.0