using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading;

namespace AsyncDelegatesExample
{
    class Program
    {
        public delegate int SomeOperation(int i);

        static int DoSomething(int i)
        {
            //something time consuming here
            Thread.Sleep(5500);
            return 2 * i;
        }

        static void Main(string[] args)
        {
            SomeOperation so = DoSomething;
            IAsyncResult iar = so.BeginInvoke(8, null, null);
            Console.WriteLine("Method executed");
            WaitHandle.
            Thread.Sleep(1000);
            while (!iar.IsCompleted)
            {
                Console.WriteLine("Method DoSomething has not finished yet");
                Thread.Sleep(1000);
            }
            Console.WriteLine("Method DoSomething has finished with result {0}", so.EndInvoke(iar));

        }
    }
}