C # Records cycle consumption time

Today wrote the Loop section code, but feel like the performance is very poor appearance, want to look at the entire cycle of execution time, at first I think of DateTime.Now, but the strange thing is, if I cycle less than 30,000 times (less than a few words) will find 2 time interval is the same! Whether it is DateTime.Now.Tick or DateTime.Now.TimeOfDay.ToString (), the Internet to find information, it seems that datetime.now accuracy is relatively low, looking for a long time finally find a solution, direct sticker Code

Private Static voidTest () { Do{Console.Write ("Number:"); intnum =Convert.ToInt32 (Console.ReadLine ()); Stopwatch SW=NewStopwatch (); Sw.                Start ();  for(inti =0; i < num; i++)                {                    intA =1; } SW.                 Stop (); Console.WriteLine ("spents:"+SW.                Elapsedticks); Console.WriteLine ("*******************************"); }  while(1==1); }

C # Records cycle consumption time