using System;

public class Program

{

    public static void Main()

    {

        Hello h = new Hello();

        h.SayHi += HandleSayHi;

        h.OnSayingHi();

    }

    public static void HandleSayHi(object sender, EventArgs args)

    {

            Console.WriteLine(sender.ToString() + " says Hello");

    }

}

​

public class Hello

{

    public event EventHandler SayHi;

    public void OnSayingHi()

    {

        if(SayHi != null)

        {

            SayHi(this, EventArgs.Empty);   

        }

    }

}