C++运算符重载 成员函数与友元函数

#include<iostream>

using namespace std;

class A

{

    int x,y;

    public:

    A(int xx,int yy):x(xx),y(yy){}

    A(){x=0;y=0;}

    A operator+(const A&b) //不加const限定，也可以

    { return A(x+b.x,y+b.y); }

    A operator-()

    { return A(-x,-y); }

    void show()

    {cout<<"x="<<x<<" y="<<y<<endl;}

};

void test_A()

{

    A a1(2008,512),a2(2013,420),a3;

    a3=a1+a2; //调用操作符重载函数: a1.oprator +(a2)

    a3.show();

    a1=-a1; //调用操作符重载函数: a1.operator -()

    a1.show();

}

/***********************

执行结果

x=4021 y=93

x=-2008 y=-512

**********************/

class B

{

    int x,y;

    public:

        B(int xx,int yy):x(xx),y(yy){}

        B(){x=0;y=0;}

        friend B operator+(const B&a,const B&b);

        friend B operator-(const B&a);

        void show()

        {cout<<"x="<<x<<" y="<<y<<endl;};

};

B operator+(const B&a,const B&b)

{return B(a.x+b.x,a.y+b.y);}

B operator-(const B&a)

{return B(-a.x,-a.y);}

/***************************

class B

{

    int x,y;

    public:

        B(int xx,int yy):x(xx),y(yy){}

        B(){x=0;y=0;}

        friend B operator+(const B&a,const B&b)

                {return B(a.x+b.x,a.y+b.y);}

        friend B operator-(const B&a)

            {return B(-a.x,-a.y);}

        void show()

        {cout<<"x="<<x<<" y="<<y<<endl;};

}

********************************/

int main()

{

    B B1(1991,1105),B2(2013,62),B3;

    B3=B1+B2; //调用操作符重载函数: a1.oprator +(a2)

    B3.show();

    B1=-B1; //调用操作符重载函数: a1.operator +()

    B1.show();

}

/****************************

运行结果：

x=4004 y=1167

x=-1991 y=-1105

Process returned 0 (0x0)   execution time : 0.021 s

Press any key to continue.

*****************************/

#include<iostream>
using namespace std;

class A
{
int x,y;
public:
A(int xx,int yy):x(xx),y(yy){}
A(){x=0;y=0;}
A operator+(const A&b) //不加const限定，也可以
{ return A(x+b.x,y+b.y); }
A operator-()
{ return A(-x,-y); }
void show()
{cout<<"x="<<x<<" y="<<y<<endl;}
};

void test_A()
{
A a1(2008,512),a2(2013,420),a3;
a3=a1+a2; //调用操作符重载函数: a1.oprator +(a2)
a3.show();
a1=-a1; //调用操作符重载函数: a1.operator -()
a1.show();
}

/***********************
执行结果
x=4021 y=93
x=-2008 y=-512
**********************/

class B
{
int x,y;
public:
B(int xx,int yy):x(xx),y(yy){}
B(){x=0;y=0;}
friend B operator+(const B&a,const B&b);
friend B operator-(const B&a);
void show()
{cout<<"x="<<x<<" y="<<y<<endl;};
};
B operator+(const B&a,const B&b)
{return B(a.x+b.x,a.y+b.y);}
B operator-(const B&a)
{return B(-a.x,-a.y);}

/***************************
class B
{
int x,y;
public:
B(int xx,int yy):x(xx),y(yy){}
B(){x=0;y=0;}
friend B operator+(const B&a,const B&b)
{return B(a.x+b.x,a.y+b.y);}

friend B operator-(const B&a)
{return B(-a.x,-a.y);}
void show()
{cout<<"x="<<x<<" y="<<y<<endl;};
}
********************************/
int main()
{
B B1(1991,1105),B2(2013,62),B3;
B3=B1+B2; //调用操作符重载函数: a1.oprator +(a2)
B3.show();
B1=-B1; //调用操作符重载函数: a1.operator +()
B1.show();
}
/****************************
运行结果：
x=4004 y=1167
x=-1991 y=-1105

Process returned 0 (0x0)   execution time : 0.021 s
Press any key to continue.

*****************************/