我对一段程序的理解，望大家指教 （对象返回值）

#include <stdio.h>#include <iostream.h>//using namespace std;class Point{public:Point(){m_x = 0;m_y = 0;cout<<"construct: x = "<<m_x<<" y = "<<m_y<<endl;}Point(unsigned int x, unsigned int y){m_x = x;m_y = y;cout<<"construct: x = "<<m_x<<" y = "<<m_y<<endl;}void print(){cout<<"x = "<<m_x<<endl;cout<<"y = "<<m_y<<endl;cout<<endl;}Point(const Point& p):m_x(p.m_x),m_y(p.m_y){cout<<"copy construcor of this from p:(m_x="<<p.m_x<<",m_y="<<p.m_y<<")"<<endl;}~Point(){cout<<"~Point():x="<<m_x<<"y="<<m_y<<endl;}friend Point operator+(Point& pt, int nOffset);friend Point operator+(int nOffset, Point& pt);public:unsigned int m_x;unsigned int m_y;};Point operator+(Point& pt, int nOffset){//Point temp=pt;//等同于Point temp(pt);初始化是调用拷贝构造函数滴。Point temp;temp = pt;//调用赋值操作符temp.m_x += nOffset;temp.m_y += nOffset;printf("where/n");return temp;}int main(int argc, char* argv[]){Point pt(10, 20);cout<<"+++++++++++++++++++++"<<endl;Point& ptt= pt+3; //这里加不加&（即Point ptt= pt+3似乎没影响），似乎结果都一样，这里有点不明白，请大家指教ptt.print();cout<<"+++++++++++++++++++++"<<endl;pt=pt+4;pt.print();cout<<"+++++++++++++++++++++"<<endl;pt = pt + 1;getchar();return 0;}/*通过对程序3进行单步调试发现：运行结果如下我的理解如下：有什么不妥的地方，请多多指教construct: x = 10 y = 20 //pt构造+++++++++++++++++++++construct: x = 0 y = 0 //temp构造wherecopy construcor of this from p:(m_x=13,m_y=23) //生成临时对象~Point():x=13y=23//析构tempx = 13y = 23+++++++++++++++++++++construct: x = 0 y = 0 //temp构造wherecopy construcor of this from p:(m_x=14,m_y=24) //生成临时对象~Point():x=14y=24 //析构temp~Point():x=14y=24 //析构临时对象，由于这里没有被赋值给另一个对象x = 14y = 24 +++++++++++++++++++++ construct: x = 0 y = 0 //temp构造wherecopy construcor of this from p:(m_x=15,m_y=25) //生成临时对象~Point():x=15y=25 //析构temp~Point():x=15y=25 //析构临时对象，由于这里没有被赋值给另一个对象~Point():x=13y=23//析构ptt~Point():x=15y=25//析构最初的pt*/