C#异步编程

static void Main(string[] args)
        {
 Console.WriteLine("方法开始："+DateTime.Now.ToString("yyyy-MM-dd hh:MM:ss"));
            var strRes = Task.Run(() => {return ReturnStr(); });
            Console.WriteLine("方法结束："+DateTime.Now.ToString("yyyy-MM-dd hh:MM:ss"));
            for (int i = 0; i < 5; i++)
            {
                Console.WriteLine(i);
            }
            Console.WriteLine("得到结果后："+DateTime.Now.ToString("yyyy-MM-dd hh:MM:ss"));
            Console.WriteLine(strRes.Result);
            Console.ReadKey();
        }
public static  string  ReturnStr()
        {
            Thread.Sleep(2000);
            return "方法执行后："+ DateTime.Now.ToString("yyyy-MM-dd hh:MM:ss");
        }

运行结果：

async & await

static void Main(string[] args)
        {
Console.WriteLine("方法开始：" + DateTime.Now.ToString("yyyy-MM-dd hh:MM:ss"));
 ReturnStr();
            for (int i = 0; i < 5; i++)
            {
                Console.WriteLine(i);
            }
            Console.WriteLine("方法结束："+DateTime.Now.ToString("yyyy-MM-dd hh:MM:ss"));
            Console.ReadKey();
        }

        public static async  Task ReturnStr()
        {
            Console.WriteLine("方法执行开始：" + DateTime.Now.ToString("yyyy-MM-dd hh:MM:ss"));
            Thread.Sleep(2000);
            var result=await Task.Run(()=>"方法执行后："+ DateTime.Now.ToString("yyyy-MM-dd hh:MM:ss"));
            Console.WriteLine(result);
        }

运行结果：

方法内等待语句须添加await