使用Async与Await进行异步编程 简单代码

        private async void AsyncMeth()
        {
            for (int i = 0; i < 5; i++)
            {
                await Task.Delay(2000);
                Console.WriteLine(i.ToString());
            }

            var res = await Add(1, 2);

            var a = (int)res;
            Console.WriteLine(a);
        }


        private async Task<int> Add(int a, int b)
        {
            return a + b;
        }

           Console.WriteLine("主线程测试开始..");

            AsyncMeth();

            Console.WriteLine("主线程测试结束..");