今天发现C#虚函数简直妙不可言....

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

namespace ConsoleApplication2
{
class Program
{
static void Main(string[] args)
{
//A a = new A();
//B b = new B();
C c = new C();
//b.GetYear();
}
}

public class A
{
public A()
{
Console.WriteLine("DEBUG: A constructing");

this.GetYear();
}

public virtual void GetYear()
{
Console.WriteLine("A");
}
}

public class B:A
{
public B():base()
{
Console.WriteLine("DEBUG: B constructing");
this.GetYear();
}

public override void GetYear()
{
//base.GetYear();
Console.WriteLine("B");
}
}

public class C : B
{
public C()
{
Console.WriteLine("DEBUG : C constructing");
this.GetYear();
}

public override void GetYear()
{
//base.GetYear();
Console.WriteLine("C");
}

}

}

运行结果:一定大出你的意料吧!



如果把代码改一下:


using System;


using System.Collections.Generic;


using System.Text;




namespace ConsoleApplication2




...{


class Program




...{


static void Main(string[] args)




...{


//A a = new A();


C c = new C();




// c.GetYear();


//b.GetYear();


}


}




public class A




...{


public A()




...{


Console.WriteLine("DEBUG: A constructing");


this.GetYear();


}




protected void GetYear()




...{


Console.WriteLine("A");


}


}




public class B:A




...{


public B():base()




...{


Console.WriteLine("DEBUG: B constructing");


this.GetYear();


}




protected void GetYear()




...{


//base.GetYear();


Console.WriteLine("B");


}


}




public class C : B




...{


public C():base()




...{


Console.WriteLine("DEBUG: C constructing");


//base.GetYear();


this.GetYear();


}




protected void GetYear()




...{


//base.GetYear();


Console.WriteLine("C");


}


}




}

通过这两个例子,终于好像彻底明白了虚函数和new(子类屏蔽父类的方法的关键字).

不过还有更cool点儿的.....请看下面的例子,仔细看小心头晕哦,哈:)


using System;


using System.Collections.Generic;


using System.Text;




namespace ConsoleApplication2




...{


class Program




...{


static void Main(string[] args)




...{


//A a = new A();


//C c = new C();


D d = new D();




// c.GetYear();


//b.GetYear();


}


}




public class A




...{


public A()




...{


Console.WriteLine("DEBUG: A constructing");


this.GetYear();


}




protected virtual void GetYear()




...{


Console.WriteLine("A");


}


}




public class B:A




...{


public B():base()




...{


Console.WriteLine("DEBUG: B constructing");


this.GetYear();


}




//protected override void GetYear()


//{


// //base.GetYear();


// Console.WriteLine("B");


//}


}




public class C : B




...{


public C():base()




...{


Console.WriteLine("DEBUG: C constructing");


//base.GetYear();


this.GetYear();


}




protected override void GetYear()




...{


//base.GetYear();


Console.WriteLine("C");


}




//protected new void GetYear()


//{


// //base.GetYear();


// Console.WriteLine("C");


//}




}




public class D : C




...{


public D()




...{


Console.WriteLine("DEBUG: D contructing");


this.GetYear();


}




}




}

怎么样,发现了吧.虚函数和new的确有很多相似的地方,甚至如果仅以实现程序为目的的话,应该可以互换的,不是吗?
听起来怎么有点玄啊!没错,肯定不是的.是很相似,不过肯定有不一样的地方.可在哪里呢?