Class C# Tutorial

using System;
interface MyInterface
{
    void MyMethodInInterface();
}
public class Base: MyInterface
{
    public void MyMethodInInterface()
    {
        Console.WriteLine("Base.MyMethodInInterface()");
    }
}
public class Derived: Base
{
    public new void MyMethodInInterface()
    {
        Console.WriteLine("Derived.MyMethodInInterface()");
    }
}
class MainClass
{
    public static void Main()
    {
        Derived der = new Derived();
        der.MyMethodInInterface();
        MyInterface helper = (MyInterface) der;
        helper.MyMethodInInterface();
    }
}
Derived.MyMethodInInterface()
Base.MyMethodInInterface()