运算符，操作符 重载

#include <iostream> using namespace std;

class people{

public:

 int a;

 int b;  

people():a(0),b(0){};

 people(int x,int y):a(x),b(y){};  

people& operator+=(const people&);  //返回值是*this

friend people operator-(const people&,const people&);  //返回值是一个新的people对象

};

people& people::operator+=(const people& p){  

this->a+=p.a;

 this->b+=p.b;

 return *this;

}

people operator-(const people& p1,const people& p2){  

people p;  

p.a=p1.a-p2.a;  

p.b=p1.b-p2.b;

 return p;

}

ostream& operator<<(ostream& os,const people& p){  

os<<"a="<<p.a<<" b="<<p.b<<endl;

 return os;//为了保证能够连接操作，返回值仍然是流。。

}

 

int main(){

 people p1(1,1);  

people p2(2,3);  

people p3 = p2-p1;  

cout<<p3;

 return 0;

}

 

 

输出：a=1 b=2