Rect

//rect.h

class Rectangular
{
private:
    int x;
    int y;
public:
    int area();
    void sethw();
};

//rect.cpp

#include "rect.h"

int Rectangular::area()
{
    return x*y;
}

void Rectangular::sethw (int h, int w)
{
    x=h;
    y=w;
}

//main.cpp

#include <iostream>
#include "rect.h"
{
    Rectangular r1, r2;
    r1.sethw (100; 100);
    r2.sethw (20; 30);

    std::cout<<"1: "<<r1.area()<<"2: "<<r2.area<<std::endl;
    std::cin.get();
    return 0;
}