Accurate test __.net for. NET Code snippet elapsed time

For a lot of just getting started friends, know the implementation of the program results, but the implementation of the program do not know how to measure, so that do not understand the efficiency of the two code analysis, think of their own is so over, so I know the way to write to everyone to see. using system; using system.data; using system.configuration; using system.collections; using system.web; using system.web.security; using system.web.ui; using system.web.ui.webcontrols; using system.web.ui.webcontrols.webparts; using system.web.ui.htmlcontrols; using system.diagnostics; Public partial class counttime : system.web.ui.page {    protected  void page_load (object sender, eventargs e)     {         stopwatch sw = new stopwatch (); &NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;SW. Start ();         for  (int i = 0; i <  100000000; i++)         {&NBSP;&NBSP;&NBSP;&NBSP;&NBsp;       int j = i + 1; &NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP}         sw. Stop ();         response.write (sw.elapsed.milliseconds / 1000d); &NBSP;&NBSP;&NBSP;&NBSP}}