//Fig 2.9: exercise 

//Class average program with sentinel-controlled repetition

//eg. clear counter add to counter average in the end

#include <iostream.h>

#include <iomanip.h>

int main()
{
	int total,				//sum
		gradeCounter,		//number of grades entered
		grade;				//one grade
	float average;			//number with decimal point for average

	//This is the initialization phase

	total = 0;
	gradeCounter = 0;		//all totals and previous counters are reset to zero in memory

	//processing phase

	cout << "Enter grade, -1 to end: ";
	
	cin >> grade;

	while ( grade != -1 ) 
	
	{
		total = total + grade;
		gradeCounter = gradeCounter + 1;
		cout << "Enter grade, -1 to end: ";
		cin >> grade;
	}

	//termination phase

	if ( gradeCounter != 0 ) 
	
	{
		average = static_cast< float > ( total ) / gradeCounter;
		cout << "Class average is " << setprecision ( 2 )
			 << setiosflags ( ios::fixed | ios::showpoint )
			 << average << endl;
	}
	
	else 
		cout << "No grades were entered" << endl;
	
	
	return  0; //Indicate that program successfully ended
}

// This shows an add and average out operation to records with no set entries
//-1 indicates that no more numbers are to be entered and the average out the sum