C#_delegate EndInvoke

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

//异步调用
//returntype EndInvoke(ref_out_argument,AsyncWaitHandle ar)

namespace Starter
{
    public delegate int DeleageteClass(out DateTime start, out DateTime stop);

    class Program
    {
        static void Main(string[] args)
        {
            DeleageteClass del = MethodA;
            DateTime start;
            DateTime stop;

            IAsyncResult ar = del.BeginInvoke(out start, out stop, null, null);

            ar.AsyncWaitHandle.WaitOne();

            //do something else

            //EndInvoke返回一个一步结果
            int elapse = del.EndInvoke(out start, out stop, ar);

            Console.WriteLine("start: "+ start.ToLongTimeString());
            Console.WriteLine("stop: " + stop.ToLongTimeString());
            Console.WriteLine("elapse: " + elapse);

            Console.ReadLine();
        }

        public static int MethodA(out DateTime start,out DateTime stop)
        {
            start = DateTime.Now;
            Thread.Sleep(5000);
            stop = DateTime.Now;
            return (stop-start).Seconds;
        }
    }

}