//This program will calculate the average sales
//over a period of years
#include <iostream>
#include <iomanip>
using namespace std;

//Global variables
int numYears;		//Number of years
double	average;	//Average sales

//Function prototype
double sales();
void averageSale(double);

int main()
{
	//Define variables.
	int year;			//Placeholder for years
	double average,		//Average sales
	       sale,   		//Sales value
		total = sales();//Accumulator for total

	//Set up numeric output formatting.
	cout << fixed << showpoint << setprecision(2);

	//Get the number of years.
	cout << "This program will calculate average sales over ";
	cout << "a period of years. How many years do you wish ";
	cout << "to average? ";
	cin >> numYears;
	cout << "\n\n";

	while (numYears < 1) //Force user to enter years greater than 1
	{
		cout << "Years must be greater than 1. Please re-enter: ";
		cin >> numYears;
	}
	//Loop for years
	for (int year = 1; year <= numYears; year++)
	{
		cout << "Year " << year << ":" << endl;
		sales();
		cout << "\n\n";
	}
	void averageSale(double total);
	return 0;
}

//Definition of average function
//This function calculates the average of sales totals
void averageSale(double total)
{
	//Calculate sales average
	average = total / (numYears * 4);
	cout << "\n\nOver a period of " << numYears * 4 << " quarters: $" << total << endl;
	cout << "Average quarterly sales for the period is: $" << average << endl;
}

//Definition of sales function
//This function calculates the total sales inputed by the user
double sales()
{
	const int quarter = 5;		//Number of quarters
	int sale[quarter],			//Each quarterly sale
		total=0,				//Total sales initializer
		count;					//Loop counter

	//Input quarterly sales
	for (count = 1; count < quarter; count++)
		{
			cout << "Enter sales amount for quarter " << count << ": ";
			cin >> sale[count - 1];
			while (sale < 0) //Force user to enter sales value above 0
			{
				cout << "Sales must be zero or greater. Please re-enter: ";
				cin >> sale[count - 1];
			}
			//Total sales
			total += sale[count - 1];
		}
	return total;
}