File:http://libg.org/code/sample.cs Help

// From http://en.wikipedia.org/wiki/C_Sharp_(programming_language)
using System;

class Employee { }

class ContractEmployee : Employee
{
}

class CastExample5
{
    public static void Main()
    {
        Employee e = new Employee();
        Console.WriteLine("e = {0}",
                       e == null ? "null" : e.ToString());

        ContractEmployee c = e as ContractEmployee;
        Console.WriteLine("c = {0}",
                           c == null ? "null" : c.ToString());
    }
}