c++之友元

#include<iostream>
using namespace std;
class Building{
    friend void goodGay(Building* building);
public:
    Building() {
        room = "客厅";
        myRoom = 卧室;
    }
:
    String room;
private myRoom;
};
//全局函数
void goodGay(Building *building) {
    cout << 好朋友正在访问" <<building->room<< endl;
    如果不将dooGay变成Building的友元函数，这里就会报错
    cout << "好朋友正在访问" << building->myRoom << endl;
}
void test() {
    Building building;
    goodGay(&building);
}
int main() {
    test();
    system(pause);
    return 0;
}

#include<iostream>
 std;

 Building{
    friend class GoodGay;
 room;
    Building();
类外写成员函数
Building::Building() {
    room = ;
    myRoom = ;
}

 GoodGay {
:
    Building* building;
    GoodGay();
     visit();
};
GoodGay::GoodGay() {
    building = new Building();
}
 GoodGay::visit() {
    cout << 好基友类正在访问：" << building->room << endl;
    cout << "好基友类正在访问：" << building->myRoom << test() {
    GoodGay gg;
    gg.visit();
}
成员函数做友元：


#include<iostream>
 Building;
 GoodGay;

要先定义GoodGay类。。。
我尝试在Building之后定义，就不行，之前也先声明了这两个类
:
    GoodGay();
    void visit();让该函数可以访问Building的私有成员
     visit2();
 building;
};

void GoodGay::visit();
;
}

GoodGay::GoodGay() {
    building =  endl;
    cout  GoodGay::visit2() {
    cout << cout << "好基友类正在访问：" << building->myRoom << endl;
}
 test2() {
    GoodGay gg;
    gg.visit2();
}
;
}