6/18 C++: class Vector

#include <iostream>
#include <cmath>
using namespace std;

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

    public:
        // 方法;功能(函式部分)
        friend void printVector(Vector v);

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

        Vector(double x, double y){
            _x = x;
            _y = y;
        }

        double length(){
            return pow( _x*_x + _y*_y, 0.5 );
        }

        Vector& setX(double x){
            _x = x;
            return *this;
        }

        Vector& setY(double y){
            _y = y;
            return *this;
        }

        double getX(){
            return _x;
        }

        double getY(){
            return _y;
        }

        void print(){
            cout << "(" << _x << "," << _y << ")" << endl;
        }


        Vector operator+(const Vector& v2){
            double newX = _x + v2._x;
            double newY = _y + v2._y;

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

};



int main(){
    Vector v1(3, 4);
    Vector v2(5, 4);

    v1.setX(5).setY(6);

    Vector v3 = v1 + v2; //v1.operator+(v2);

    v1.print();
    v2.print();
    v3.print();

    return 0;
}