using System;

public class Program

{

    public static void Main()

    {

        A a = new A();

        OverrideA overrideA = new OverrideA();

        NewA newA = new NewA();

​

        IShow iOverrideA = overrideA;

        IShow iNewA = newA;

        // Use the most concrete type

        a.ShowData(); // prints "This is Class A"

        overrideA.ShowData(); // prints "This is Class OverrideA"

        newA.ShowData(); // prints "This is Class NewA"

        // Use IShow type - key difference is here

        iOverrideA.ShowData(); // prints "This is Class OverrideA"

        iNewA.ShowData(); // prints "This is Class A"

    }

}

​

interface IShow

{

    public void ShowData();

}

​

class A : IShow

{

    public virtual void ShowData()

    {

        Console.WriteLine("This is Class A");

    }

}

​

class OverrideA : A

{

    public override void ShowData()

    {

        Console.WriteLine("This is Class OverrideA");

    }

}

​

class NewA : A

{

    public new void ShowData()

    {

        Console.WriteLine("This is Class NewA");

    }

}