/*
 * Write a program called points.cc that:
 *
 * 1. Repeatedly reads in from the user the coordinates of two points:
 *    (x1, y1) and (x2, y2)
 * 2. Calls a function that calculates and returns the distance between
 *    the two points
 * 3. Prints out the distance calculated
 * 4. Exits when the points entered are (0, 0) and (0, 0) 
 *
 * Note: The distance between two points (x1, y1) and (x2, y2) can be
 * calculated by taking the square root of [ (x2 - x1)^2 + (y2 - y1)^2 ]
 * where ^ means "to the power of"
 *
 * For example:
 *
 * Enter x1 and y1:
 * 0 0
 * Enter x2 and y2:
 * 1 1
 * The distance between the two points is 1.41421
 * Enter x1 and y1:
 * 0 0
 * Enter x2 and y2:
 * 3 4
 * The distance between the two points is 5
 * Enter x1 and y1:
 * 0 0
 * Enter x2 and y2:
 * 0 0
 */
#include <iostream>
#include <cmath>

using namespace std;

float d(int, int, int, int);

int
main()
{
    int x1, y1, x2, y2;
    float z;

    cout << "Enter x1 and y1:" << endl;
    cin >> x1 >> y1;

    cout << "Enter x2 and y2:" << endl;
    cin >> x2 >> y2;

    while (!((x1 == 0) && (y1 == 0) && (x2 == 0) && (y2 == 0))) {

	    z = d(x1, y1, x2, y2);
    
	    cout << "The distance between the two points is " << z << endl;

	    cout << "Enter x1 and y1:" << endl;
	    cin >> x1 >> y1;

	    cout << "Enter x2 and y2:" << endl;
	    cin >> x2 >> y2;

	}   

    return (0);
}

float
d(int x1, int y1, int x2, int y2)
{
    return sqrt((x2 - x1) * (x2 - x1) + (y2 - y1) * (y2 - y1));
}