c++ primer plus 第十章-编程题6

/* ------------------------------------------- ad: x = 10.5 , y = 6.5 ae: x = 4.44 , y = 2.11 ad + ae: x = 14.94 , y = 8.61 x = 0 , y = 0 x = 0 , y = 0 ------------------------------------------- *///Move.h#ifndef ___0_10_6__Move__#define ___0_10_6__Move__class Move {private:    double x;    double y;public:    Move(double a = 0, double b = 0);    void showmove() const;    Move add(constMove & m) const;    void reset(double a =0, double b =0);};#endif /* defined(___0_10_6__Move__) *///Move.cpp#include <iostream>#include "Move.h"Move::Move(double a,double b) {    x = a;    y = b;}void Move::showmove()const {    std::cout <<"x = " << x <<" , " << "y = " <<y << "\n";}Move Move::add(constMove & m) const {    Move n;    n.x = x + m.x;    n.y = y + m.y;    return n;}void Move::reset(double a,double b) {    x = a;    y = b;}//main.cpp#include <iostream>#include "Move.h"int main() {    using std::cout;    Move ad(10.5,6.5);    Move ae(4.44,2.11);    Move sum;    cout << "ad:\n";    ad.showmove();    cout << "ae:\n";    ae.showmove();    sum = ad.add(ae);    cout <<"ad + ae:\n";    sum.showmove();    ad.reset();    ae.reset();    ad.showmove();    ae.showmove();    return 0;}