C# overload、override、hiding区别

overload（重载）表示在同一个作用域中有多个名称相同但签名不同的方法。

 1 class DoThings
 2 {
 3     public string DoThingsManyWays(int num)
 4     {
 5         return "I'm overloading number things.";
 6     }
 7 
 8     public string DoThingsManyWays(string str)
 9     {
10         return "I'm overloading string things.";            
11     }
12 }

override（重写）表示在子类中重写方法的实现，父类中必须声明为virtual。

 1 class Parent
 2 {
 3     public virtual string DoThings()
 4     {
 5         return "I'm parent class virtual method.";
 6     }
 7 }
 8 
 9 class Child : Parent
10 {
11     public override string DoThings()
12     {
13         return "I'm child class override method.";
14     }
15 }

子类可以使用hiding修改父类方法的行为，但new将被父类中由virtual修饰的同名方法所覆盖。

 1 class Parent
 2 {
 3     public string Do()
 4     {
 5         return "I'm Parent.Do.";
 6     }
 7 }
 8 
 9 class Child : Parent
10 {
11     new public string Do()
12     {
13         return "I'm Child.Do.";
14     }
15 }

输出结果：

 1 Parent parent = new Parent();
 2 Child child = new Child();
 3 
 4 Console.WriteLine(child.DoThings());
 5 // I'm child class override method.
 6 
 7 Console.WriteLine((child as Parent).DoThings());
 8 // I'm child class override method.
 9 
10 Console.WriteLine(parent.Do());
11 // I'm Parent.Do.
12 
13 Console.WriteLine(child.Do());
14 // I'm Child.Do.
15 
16 Console.WriteLine((child as Parent).Do());
17 // I'm Parent.Do.

程序代码见：https://github.com/meantobe/blog/tree/master/CSharp/OverrideAndOverload

参考资料：

1. http://stackoverflow.com/questions/673721/overloading-and-overriding/673754

2. http://www.hanselman.com/blog/WhatGreatNETDevelopersOughtToKnowMoreNETInterviewQuestions.aspx

3. http://www.cnblogs.com/lipu/archive/2010/11/12/1875095.html

posted @ 2013-10-21 10:26  meantobe  阅读(252)  评论(0)  编辑  收藏  举报