//
// Created by pengshuai on 2022年3月8日.
//

/**
 * 基类指针指向继承类对象,则调用继承类对象的函数;
 * int main()必须声明为Base类的友元,否则编译失败。 编译器报错: ptr无法访问私有函数。
 * 当然,把基类声明为public, 继承类为private,该问题就不存在了。
 */

#include<iostream>
using namespace std;

/*class Derived;

class Base
{
private:
 virtual void fun() { cout << "Base Fun"; }
 friend int main();
};

class Derived: public Base
{
public:
 void fun() override { cout << "Derived Fun"; }
};

int main()
{
 Base *ptr = new Derived;
 ptr->fun();
 return 0;
}*/

class Derived;

class Base
{
public:
 virtual void fun() { cout << "Base Fun"; }
};

class Derived: public Base
{
private:
 void fun() override { cout << "Derived Fun"; }
};

int main()
{
 Base *ptr = new Derived;
 ptr->fun(); // Derived Fun
 return 0;
}