友元函数和运算符重载-蒲公英云

友元函数和运算符重载

//友元函数
/*
class A{
    //友元函数
    friend void modify_i(A *p, int a);
private:
    int i;
public:
    A(int i){
        this->i = i;
    }
    void myprint(){
        cout << i << endl;
    }
};
//友元函数的实现，在友元函数中可以访问私有的属性
void modify_i(A *p, int a){
    p->i = a;
}
void main(){
    A* a = new A(10);
    a->myprint();
    modify_i(a,20);
    a->myprint();
    system("pause");
}
*/
/*
//友元类
class A{        
    //友元类
    friend class B;
private:
    int i;
public:
    A(int i){
        this->i = i;
    }
    void myprint(){
        cout << i << endl;
    }    
};
class B{
public:
    //B这个友元类可以访问A类的任何成员
    void accessAny(){
        a.i = 30;        
    }
private:
    A a;
};
*/
//运算符重载
/*
class Point{
public:
    int x;
    int y;
public:
    Point(int x = 0, int y = 0){
        this->x = x;
        this->y = y;
    }
    void myprint(){
        cout << x << "," << y << endl;
    }
};
//重载+号
Point operator+(Point &p1, Point &p2){
    Point tmp(p1.x + p2.x, p1.y + p2.y);
    return tmp;
}
//重载-号
Point operator-(Point &p1, Point &p2){
    Point tmp(p1.x - p2.x, p1.y - p2.y);
    return tmp;
}
void main(){
    Point p1(10,20);
    Point p2(20,10);
    Point p3 = p1 + p2;
    p3.myprint();
    system("pause");
}
*/
//成员函数，运算符重载
/*
class Point{
public:
    int x;
    int y;
public:
    Point(int x = 0, int y = 0){
        this->x = x;
        this->y = y;
    }
    //成员函数，运算符重载
    Point operator+(Point &p2){
        Point tmp(this->x + p2.x, this->y + p2.y);
        return tmp;
    }
    void myprint(){
        cout << x << "," << y << endl;
    }
};
void main(){
    Point p1(10, 20);
    Point p2(20, 10);
    //运算符的重载，本质还是函数调用
    //p1.operator+(p2)
    Point p3 = p1 + p2;
    p3.myprint();
    system("pause");
}
*/
//当属性私有时，通过友元函数完成运算符重载
class Point{
    friend Point operator+(Point &p1, Point &p2);
private:
    int x;
    int y;
public:
    Point(int x = 0, int y = 0){
        this->x = x;
        this->y = y;
    }    
    void myprint(){
        cout << x << "," << y << endl;
    }
};
Point operator+(Point &p1, Point &p2){
    Point tmp(p1.x + p2.x, p1.y + p2.y);
    return tmp;
}
void main(){
    Point p1(10, 20);
    Point p2(20, 10);
    //运算符的重载，本质还是函数调用
    //p1.operator+(p2)
    Point p3 = p1 + p2;
    p3.myprint();
    system("pause");
}