Question

C++.阅读程序，写出运行结果,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

//obj1+obj2 相当于调用了obj1.operator+(obj2)
Sample obj1(5),obj2(10),obj3;//相当于obj1.x = 5； obj2.x=10；obj3.x没有初始
obj3=obj1+obj2;//将obj3指向Sample(obj1.x+obj2.x),即obj3.x=5+10
obj1-obj2;//返回Sample(obj1.x-obj2.x).disp();

Answer 2

x=15
x=-5
这是我运行之后出来的，应该是正确的。