Question

C++.阅读程序，写出运行结果,急求大神。

#include "iostream.h"

class Sample{

private: int x;

public : Sample( ){ }

Sample(int a ){x=a;
}

void
disp(){cout<<"x="<<x<<endl;}

Sample
operator+(Sample &);

friend Sample operator-(Sample &,Sample &);

};

Sample Sample ::operator+(Sample
&s){return Sample(x+s.x); }

Sample operator-(Sample &s1,Sample
&s2){return Sample(s1.x-s2.x); }

void main(){ Sample obj1(5),obj2(10),obj3;

obj3=obj1+obj2;

obj3.disp(); (obj1-obj2).disp();

}

Answer 1

x=15
x=-5
obj1+obj2调用Sample成员函数中得加号运算符的重载函数，返回以obj1x的值与obj2x的值的和作为参数调用Sample的构造函数创建的临时对象。
而obj1-obj2调用减号运算符的重载函数，返回以obj1x的值与obj2x的值的差作为参数调用Sample的构造函数创建的临时对象。