/*

Basic Program File Structure and Sample Function Call

File: sum.cpp
Version: 3.1
Created: 9/24/96
Last updated: 10/20/99
Written by: Dr. C. S. Tritt

*/

#include <iostream>  // Header for stream I/O.
#include <iomanip> // Header for I/O manipulators.

using namespace std;

// Function declaration (prototype) with default values.

float sum(float required_term, float optional_term = 0.0);

// Main program

int main(void)
{
// Declare variables.  Some programmers like to declare their variables just
// before use.  I like to declare all of mine at the top a each function.

	int p; //  Output numeric precision.
	float a; // Units and description of a.
	float b; // Units and description of b.
	
	cout.setf(ios::showpoint); // Show decimal points.  Good until explicitly changed.

	cout << "Enter the output precision (an integer): ";
	cin >> p;
	if (!cin)
	{
		cout << "Input error.  Aborting.\n";
		return 1;
	}
	cout << setprecision(p);  // Set the precision.  Good until explicitly changed.

	cout << "Enter two real numbers to be summed: ";
	cin >> a >> b;
	if (!cin)
	{
		cout << "Input error.  Aborting.\n";
		return 2;
	}

	cout << "Entered values: a = " << a << " and b = " << b << endl;
	cout << "So sum(a, b) = " << sum(a, b) << endl;
	cout << "And sum(a) = " << sum(a) << endl;

	return 0;
}

// Define the sum function.

float sum(float x, float y)
{
	// This function returns the sum of its arguments.
	
	return (x + y);
}