Class demo

// sp0203.cpp : Defines the entry point for the console application.
//

#include "stdafx.h"
#include <iostream>
#include <cstdlib>
#include <cmath>

using namespace std;

class Rectangle {
    double sideA, sideB;
public:
    Rectangle() :sideA(0), sideB(0){};
    Rectangle(double a, double b) : sideA(a), sideB(b) {}
    Rectangle(const Rectangle &r);
    void get_sides(double *a, double *b);
    void set_sides(double a, double b);
    double get_area() { return sideA*sideB; }
    double get_perimeter() { return 2*(sideA+sideB); }
    void show();
    Rectangle operator+(Rectangle &Rect);
    Rectangle operator-(Rectangle &Rect);
    Rectangle operator=(const Rectangle &Rect);
    bool operator<(Rectangle &Rect)
    {
        return get_area() < Rect.get_area();
    }
    bool operator>(Rectangle &Rect)
    {
        return get_area() > Rect.get_area();
    }
    bool operator==(Rectangle &Rect)
    {
        return get_area() == Rect.get_area();
    }
    bool operator!=(Rectangle &Rect)
    {
        return get_area() == Rect.get_area();
    }
};

Rectangle::Rectangle(const Rectangle &r)
{
    sideA = r.sideA;
    sideB = r.sideB;
}
void Rectangle::get_sides(double *a, double *b)
{
    *a = sideA;
    *b = sideB;
}
void Rectangle::set_sides(double a, double b)
{
    if (a < 0 || b < 0)
        throw "Side is negative";
    sideA = a;
    sideB = b;
}
void Rectangle::show()
{
    std::cout << "Side A=" << sideA << ", side B=" << sideB << std::endl;
}
Rectangle Rectangle::operator+(Rectangle &Rect)
{
    return Rectangle(fmax(sideA, Rect.sideA), fmax(sideB, Rect.sideB));
}

Rectangle Rectangle::operator-(Rectangle &Rect)
{
    return Rectangle(fmin(sideA, Rect.sideA), fmin(sideB, Rect.sideB));
}

Rectangle Rectangle::operator=(const Rectangle &Rect)
{
    if (this == &Rect)
        return *this;
    sideA = Rect.sideA;
    sideB = Rect.sideB;
    return *this;
}



int _tmain(int argc, _TCHAR* argv[])
{
    Rectangle r1(20, 10),r2(r1);
    r1.show();
    cout << r1.get_area();
    if (r1 == r2) r2.show();
    return 0;
}