using System;

public class Program

{

    public static void Main()

    {

        Exception d1 = new DerivedException();

        if( d1 is BaseException )

            Console.WriteLine("Base Exception");

​

        if( d1 is DerivedException )

            Console.WriteLine("Derived Exception");

​

    }

    public class BaseException : Exception {}

    public class DerivedException : BaseException {}

}