11.4.2重学C++之【类做友元】

#include<stdlib.h>
#include<iostream>
#include<string>
using namespace std;


/*
    4.4.2 类做友元
*/


class Building; // 声明Building类，后续会写，防止Goodgay类中引用时报错


class Goodgay{
public:
    void visit();
    Goodgay(); // 构造函数
private:
    Building * building;
};


class Building{

    //告诉编译器 goodGay类是Building类的好朋友，可以访问到Building类中私有内容
    friend class Goodgay;

public:
    string setting_room;
private:
    string bed_room;
public:
    Building(); // 构造函数声明
};



Goodgay::Goodgay(){
    building = new Building; // 在堆区创建对象

}
void Goodgay::visit(){
    cout << "朋友类正在访问：" << building->setting_room << endl;
    cout << "朋友类正在访问：" << building->bed_room << endl; // 正常无法访问，会报错；声明友元后可访问
}
Building::Building(){ // 类外写成员函数，实现构造函数，注意需要在函数名前加作用域
    // 初始化赋值
    setting_room = "客厅";
    bed_room = "卧室";
}



void test1(){
    Goodgay gg;
    gg.visit();
}


int main()
{
    test1();

    system("pause");
    return 0;
}