using System; using System.Collections.Generic; using System.Text; using System.Threading; public delegate int BinaryOp(int x, int y); class Program { static void Main(string[] args) { BinaryOp b = new BinaryOp(Add); IAsyncResult iftAR = b.BeginInvoke(10, 10, null, null); while (!iftAR.AsyncWaitHandle.WaitOne(2000, true)) { Console.WriteLine("Doing more work in Main()!"); } int answer = b.EndInvoke(iftAR); Console.WriteLine("10 + 10 is {0}.", answer); } static int Add(int x, int y) { Console.WriteLine("Add() invoked on thread {0}.", Thread.CurrentThread.GetHashCode()); Thread.Sleep(5000); return x + y; } }