虚方法笔记

没用virtual时的情况：

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

namespace ConsoleApplication1
{
    class Program
    {
        static void Main(string[] args)
        {
            B b = new B();//此时b的内容是：A.F()和B.F()
            A a = b; //此时a的内容是A.F()
            a.F();
            b.F();
            Console.Read();
        }
    }
    //创建类A
    class A
    { 
     public void  F()
     {
     Console.WriteLine ("A.F()");
     }
    }
    //创建类B 继承于A
    class B:A 
    {
        public new void F()
        {
            Console.WriteLine("B.F()");
        }
    }
}

使用virtual

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

namespace ConsoleApplication1
{
    class Program
    {
        static void Main(string[] args)
        {
            C c = new C();//此时a b c的内容是c.F()
            B b = c;
            A a = c; 
            a.F();
            b.F();
            c.F();
            Console.Read();
        }
    }
    //创建类A
    class A
    { 
     public virtual void F()
     {
     Console.WriteLine ("A.F()");
     }
    }
    //创建类B 继承于A
    class B:A 
    {
        public override  void F()
        {
            Console.WriteLine("B.F()");
        }
    }
    //创建类C 继承于B
    class C : B
    {
        public override void F()
        {
            Console.WriteLine("C.F()");
        } 
    }
}