方法一：     //实例化一个计时器  Stopwatch watch = new Stopwatch();  //开始计时  watch.Start();    //此处为要计算的运行代码  for (int i = 1; i < 1000000; i++) { }   // Execute the task to be timed    //结束计时  watch.Stop();    //获取当前实例测量得出的总运行时间（以毫秒为单位）  string time = watch.ElapsedMilliseconds.ToString();  //说明：Stopwatch提供了几个方法用以控制Stopwatch对象。Start方法开始一个计时操作，Stop方法停止计时。为避免这种情况，在第二次计时前用Reset方法将对象归零     Console.WriteLine("Elapsed: {0}",watch.Elapsed);  Console.WriteLine("In milliseconds: {0}",watch.ElapsedMilliseconds);  Console.WriteLine("In timer ticks: {0}",watch.ElapsedTicks);      方法二：    DateTime startTime = DateTime.Now;  Console.WriteLine ("Started: {0}", startTime);     // Execute the task to be timed  for (int i=1; i < 100000; i++){}      DateTime stopTime = DateTime.Now;  Console.WriteLine ("Stopped: {0}", stopTime);    TimeSpan elapsedTime = stopTime - startTime;  Console.WriteLine ("Elapsed: {0}", elapsedTime);  Console.WriteLine ("in hours       :" + elapsedTime.TotalHours);  Console.WriteLine ("in minutes     :" + elapsedTime.TotalMinutes);  Console.WriteLine ("in seconds     :" + elapsedTime.TotalSeconds);  Console.WriteLine ("in milliseconds:" + elapsedTime.TotalMilliseconds);