全局函数做友元 :(1)类中写 friend void func(){};
(2)为了好友可以访问我当前的私有属性
整个类做友元类 :(1)类中写 friend class Person;
(2)友元类时单向的(A是B的友元类,但B不是A的友元类),不 可传递的(A是C,B是C友元类,A和B不是友元类)
某个成员函数做友元:(1)friend void goodGay :: visit()
フレンドクラスをケース-----
#include<iostream>
#include<string>
using namespace std;
//第一个类
class Buildings
{
friend class googGay;
public:
Buildings()
{
this->m_BedRoom="卧室";
this->m_SittingRoom="客厅";
}
private:
string m_SittingRoom;
string m_BedRoom;
};
//第二个类
class googGay
{
public:
googGay();
void visit();
private:
Buildings * building;
};
//类外实现
googGay::googGay()
{
building = new Buildings;
}
void googGay::visit()
{
cout<<"朋友正在访问"<<building->m_BedRoom<<endl;
cout<<"朋友正在访问"<<building->m_SittingRoom<<endl;
}
void test01()
{
googGay gg;
gg.visit();
}
int main()
{
test01();
return 0;
}
ケースII - フレンド関数
#include<iostream>
#include<string>
using namespace std;
class Buildings
{
friend void test01(); //声明友元函数
public:
Buildings()
{
this->m_BedRoom="卧室";
this->m_SittingRoom="客厅";
}
private:
string m_SittingRoom;
string m_BedRoom;
};
void test01()
{
Buildings *p= new Buildings;
cout<<"朋友正在访问"<<p->m_BedRoom<<endl;
cout<<"朋友正在访问"<<p->m_SittingRoom<<endl;
}
int main()
{
test01();
return 0;
}