4.4.2 类做友元

关键步骤:
在另一个类中使用 friend class 类名

拓展:

在类外写成员函数(已在类内声明, 实现可以写在外面):

//类外写成员函数
Building::Building()
{m_SittingRoom = "客厅";m_BedRoom = "卧室";
}GoodGay::GoodGay()
{//创建建筑物对象building = new Building;
}

全部代码:

#include<iostream>
using namespace std;
#include<string>
//类做友元class Building;
class GoodGay
{
public:GoodGay();void visit();//参观函数 访问Buiding中的属性Building* building;};class Building
{//GoodGay类是本类的好朋友, 可以访问该类中私有对象friend class GoodGay;public:Building();
public:string m_SittingRoom;//客厅private:string m_BedRoom;
};//类外写成员函数
Building::Building()
{m_SittingRoom = "客厅";m_BedRoom = "卧室";
}GoodGay::GoodGay()
{//创建建筑物对象building = new Building;
}void GoodGay::visit()
{cout << "好基友类正在访问: " << building->m_SittingRoom<<endl;cout << "好基友类正在访问: " << building->m_BedRoom << endl;}void test01()
{GoodGay gg;gg.visit();
} int main()
{test01();system("pause");return 0;
}