第十二周项目训练1 阅读程序

#include <iostream>
using namespace std;
class Sample
{
private:
int x;
public:
Sample () { }
Sample(int a){x=a;}
void disp(){cout<<"x="<<x<<endl;}
friend Sample operator+( Sample &s1, Sample &s2);//友元函数
};
Sample operator+( Sample &s1, Sample &s2)  //运算符+重载
{
return Sample(s1.x+s2.x);
}

int main()
{
Sample obj1(10);
Sample obj2(20);
Sample obj3;
obj3=obj1+obj2;
obj3.disp();
return 0;
}