C#拾遗系列(9):继承、接口、扩展方法、分部类、类操作、Ref and Out、可空类型

wangdeshui

本文内容：

   

• 继承   
  
• Equal示例   
  
• 结构和类   
  
• 属性   
  
• Ref and Out   
  
• 类操作   
  
• 扩展方法   
  
• 接口   
  
• 可空类型   
  
• 分部类
  

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1. 继承
<div style="font-size: 10pt; color: gray; font-family: consolas;">using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
namespace NetTest
{
    public class Animal
    {
        public virtual void Fly()
        {
            Console.Out.WriteLine("Animal Fly");
            Console.Out.WriteLine("----------------------------");
        }
    }
    public class Dog : Animal
    {
        public new virtual void Fly()
        {
            base.Fly();
            Console.Out.WriteLine("Dog  can't Fly");
            Console.Out.WriteLine("----------------------------");
        }
        //也可以，但子类不能再覆盖了
        //public new  void Fly()
        //{
        //    base.Fly();
        //    Console.Out.WriteLine("Dog can't Fly");
        //    Console.Out.WriteLine("----------------------------");
        //}               
    }
    public class Cat : Animal
    {
        public override void Fly()
        {
            base.Fly();
            Console.Out.WriteLine("Cat can't fly");
            Console.Out.WriteLine("----------------------------");
        }
 
        public override string ToString()
        {
            return "I am a happy cat,wow";
        }
 
    }
 
    public class InheritTest
    {
        public void Test()
        {
            /*
           new 和 overide的区别是，当把子类付给父类变量时，new 将调用父类的方法，而override将调用子类的方法       
           */
            Animal dog = new Dog();
            dog.Fly();
            /* 输出
            Animal Fly   
            */
 
            Animal cat = new Cat();
            cat.Fly();
 
            /* 输出
            Animal fly
            Cat can't Fly           
            */
            Console.Out.WriteLine(cat.ToString());
 
        }
    }
}
 
2. Equal 示例