4is和as运算符在接口和类中的使用.avi

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace IsAndAsDemo
{
    public interface Italkable
    {
        void Talk();
    }

    public class Man:Italkable
    {

        public void Talk()
        {
            Console.WriteLine("男人在说话");
        }
    }

    public class Duck : Italkable
    {

        public void Talk()
        {
            Console.WriteLine("鸭子嘎嘎叫");
        }
    }

    public static class Notalk
    {
        public static void Talk(Italkable target)
        {
            target.Talk();
        }

        public static void Talk2(object obj)
        {
            Italkable it = null;
            if (obj is Italkable)
            {
                it = (Italkable)obj;
                it.Talk();
            }
            else
            {
                Console.WriteLine("类型有误");
            }
        }

        public static void Talk3(object obj)
        {
            Italkable it = null;
            it = obj as Italkable;
            if (it != null)
            {
                it.Talk();
            }
            else
            {
                Console.WriteLine("类型有误");
            }
        }

        public static void Talk4(object obj)
        {
            Italkable it = null;
            if (obj is Italkable)
            {
                it = obj as Italkable;
                it.Talk();
            }
        }
    }

    class Program
    {
        static void Main(string[] args)
        {
            Man m = new Man();
            Duck d = new Duck();
            Notalk.Talk(m);
            Notalk.Talk(d);

            Notalk.Talk2(1);
            Notalk.Talk2("123");
            Notalk.Talk2(m);
            Notalk.Talk2(d);

            Notalk.Talk3(1);
            Notalk.Talk3("123");
            Notalk.Talk3(m);
            Notalk.Talk3(d);
        }
    }
}