async & await 异步编程小示例，一看就懂

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

namespace ConAppAsync
{
    class Program
    {

        //第一步，创建一个普通的耗时的方法
        static string Greeting(string name)
        {
            Thread.Sleep(3000);
            return String.Format("Hello, {0}", name);
        }

        //第二步，用一个异步方法包装上面的方法
        static Task<string> GreetingAsync(string name)
        {
            return Task.Run<string>(() =>
            {
                return Greeting(name);
            });
        }

        //第三步，再创建一个能调用上面的异步方法的方法, 加关键字 async

        private async static void CallWithAsync()
        {
            //some other tasks

            string result = await GreetingAsync("王海滨");

            //we can add multiple "await" in same "async" method
            string result1 = await GreetingAsync("Ahmed");
            string result2 = await GreetingAsync("Every Body"); 
            Console.WriteLine(result+result1+result2);
        }

        static void Main(string[] args)
        {
            //最后在主入口调用上面的方法，和调用普通方法一样
            CallWithAsync();
            int length = 100;
            for (int i = 0; i < length; i++)
            {
                Console.WriteLine(i);
            }
            Console.ReadKey();
        }
    }
}