c#判断一段代码运行所花费的时间

//定义一个时间对象
            System.Diagnostics.Stopwatch oTime = new System.Diagnostics.Stopwatch();
            oTime.Start(); //记录开始时间
            for (int i = 0; i < 10000; i++) {
                int a = i + 25160;
                int b = a - 1000;
            }
            Thread.Sleep(1500);
                oTime.Stop(); //记录结束时间
                MessageBox.Show(oTime.Elapsed.Seconds+"秒"+oTime.Elapsed.Milliseconds + "毫秒");