About Virtual Classes in c#

The trick is that you can use a reference to the base class to reference an inherited one and, at runtime, when you call a virtual function using that reference, the overridden one in the inherited class is called. Consider the code below:

class BaseClass
{
   public virtual void Test()
   {
      Console.WriteLine("BaseClass:Test()");
   }
}

class ChildClassA : BaseClass
{
   public override void Test()
   {
      Console.WriteLine("ChildClassA:Test()");
   }
}

class ChildClassB : BaseClass
{
   public override void Test()
   {
      Console.WriteLine("ChildClassB:Test()");
   }
}

Now suppose that you write something like this:

BaseClass obj = new ChildClassA();
obj.Test();
obj = ChildClassB();
obj.Test()

The output that you get is something like this:

ChildClassA:Test()
ChildClassB:Test()

There is no such thing as a virtual class.
Surely you must confuse classes with methods.
Please read some very basic documentation about object orientated programming.

My dear Friend,
Inheritance is the sole feature of Polymorphism by creating base class child class relationship.

by using this relationship by creating base class instances which can references the child class members which are inherited only.

So,

class base
    {
        public virtual int sum(int a,int b)
        {  return (a+b);}
    }

    class child
    {
        public override int sum(int a, int b)
        {  return (a+b)/10 ;   }
    }
    class Main
    {
      base b =new child();
      b.sum(10,10);
           //this gives ans 2 since it calls child class inherited method
           // this is only possible through inheritance and it code reusability                    
    }

If u are satisfied with this ans then give feed back.

you can use following link:-
http://msdn.microsoft.com/en-us/library/9fkccyh4(v=vs.80).aspx[^]