5/29 C++: class Point2D

/* Point2D.h */
#include <iostream>
using namespace std;

class Point2D{
    private:
        // 資料(變數部分)
        int _x; // 加底線 避免名稱上衝突
        int _y;

    public:
        // 方法;功能(函式部分)
        friend void OutputPoint2D(Point2D p);

        Point2D(){
            _x = 0;
            _y = 0;
        }

        Point2D(int x, int y){
            _x = x;
            _y = y;
        }

        Point2D operator*(Point2D v2){
            int newX = _x * v2._x;
            int newY = _y * v2._y;

            Point2D v3(newX, newY);
            return v3;
        }

};

void OutputPoint2D(Point2D v){
    cout << "(" << v._x << "," << v._y << ")" << endl;
}

/* Point2D.h */

int main(){
    int x, y;

    cin >> x >> y;
    Point2D p1(x, y);
    cin >> x >> y;
    Point2D p2(x, y);

    Point2D p3;
    p3 = p1 * p2;
    OutputPoint2D( p3 );
    return 0;
}