using System;

public class Program

{

    public static void Main()

    {

        // declared type vs instances type.

        // doesn't matter what you cast c to, with the overrides it still calls the C types method.

        var c  = new C();

        c.DoStuff();

        var b = (B)c;

        b.DoStuff();

        var a = (A)c;

        a.DoStuff();

        // but with new / method hiding, it matters what you cast an E to.

        var e  = new E();

        e.DoStuff();

        var d = (D)e;

        d.DoStuff();

        var a2 = (A)e;

        a2.DoStuff();

    }

}

/*

A -> B  -> C

  -> D -/> E  (-/> because D's method is sealed and E's method uses new to hide D's.)

*/

​

public class A

{

    public virtual void DoStuff()

    {

        Console.WriteLine("HI, i'm a.");

    }

}

​

public class B : A

{

    public override void DoStuff()

    {

        Console.WriteLine("HI, i'm a,b.");

    }

}

​

public class C : B

{

    public override void DoStuff()

    {

        Console.WriteLine("HI, i'm a,b,c.");

    }

}

​

public class D : A

{

    public sealed override void DoStuff()

    {

        Console.WriteLine("HI, i'm a,d.");

    }

}

​

public class E : D

{

    public new void DoStuff() // couldn't do override because D's is sealed.

    {

        Console.WriteLine("HI, i'm a,d,e.");

    }

}