里氏替换原则

里氏替换原则是指，对于已经继承了父类的子类，可以用父类容器来装载子类对象，便于对象的管理与存储。而在需要执行子类内部的具体逻辑时，则搭配is与as关键字来使用。is关键字用于判断某个对象是否属于某个类，若是则返回True，否则返回False；as关键字用于将某个对象转换为某个类内的对象，若转换成功，则返回转换成对应类的对象，若转换失败则返回null。

namespace ConsoleApp5
{
    class GameObject { }

    class Player : GameObject 
    {
        public void PlayerAtk() 
        {
            Console.WriteLine("玩家攻击");
        }
    }
    class Monster : GameObject 
    {
        public void MonsterAtk()
        {
            Console.WriteLine("怪物攻击");
        }
    }

    class Boss : GameObject
    {
        public void BossAtk()
        {
            Console.WriteLine("Boss攻击");
        }
    }
    class Program
    {
        static void Main(string[] args)
        {
            //里氏替换
            GameObject player = new Player();
            GameObject monster = new Monster();
            GameObject boss = new Boss();

            GameObject[] objects = new GameObject[] { new Player(),new Monster(),new Boss()};
            //利用is与as搭配使用，先判断对象是否属于，在转换为对应对象并调用对应方法
            for (int i = 0; i < objects.Length; i++)
            {
                if (objects[i] is Player)
                {
                    Player p = objects[i] as Player;
                    p.PlayerAtk();
                    //也可写作(objects[i] as Player).PlayerAtk()
                }
                else if (objects[i] is Monster)
                {
                    (objects[i] as Monster).MonsterAtk();
                }
                else if (objects[i] is Boss)
                {
                    (objects[i] as Boss).BossAtk();
                }
            }
        }
    }
}