第十二周—阅读程序（1）

#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;}

运行结果：