友元函数和运算符重载

深藏阁楼爱情的钟 2022-06-11 07:08 190阅读 0赞

//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");
    }