如何精確計算時間到微秒級

 一、

windows系統中取得微妙和毫秒級的時間2008-04-23 11:57

windows系統中得到精確到微妙的時間(通過cpu頻率計算) #include <windows.h> #include <iostream> (取得cpu頻率) LARGE_INTEGER t1,t2,feq; QueryPerformanceFrequency(&feq);//每秒跳動次數 QueryPerformanceCounter(&t1);//測前跳動次數 for(int i = 0;i<10000;i++); QueryPerformanceCounter(&t2);//測後跳動次數 double d=((double)t2.QuadPart-(double)t1.QuadPart)/((double)feq.QuadPart);//時間差秒 std::cout<<d<<std::endl; windows系統中得到精確到毫妙的時間 DWORD GetTickCount(VOID) ; SDk: The GetTickCount function retrieves the number of milliseconds that have elapsed since Windows was started. CTime t = CTime::GetCurrentTime(); SDK:This method obtains a CTime object that represents the current time.   二、

我最初用的函數是timeGetTime（），該函數只能精確到ms，具體用法如下

         #include <mmsystem.h>

         DOWD begin, end;

         begin = timeGetTime();

        //你要計算的程式片斷

         end = timeGetTime();

          CString strTime;
         strTime.Format("%d",end - start);

           最後在你的工程裡面設定linker-input-Additional Dependencies 加上Winmm.lib

           如果要顯示微妙級的就不夠用了，可以採用系統的計數器來實現。

           LARGE_INTEGER frequency ;
           QueryPerformanceFrequency(&frequency );
   
            LARGE_INTEGER start, end;
            QueryPerformanceCounter(&start);
            //你要計算的程式片斷  
 
           QueryPerformanceCounter(&end);

           int time=( ((end.QuadPart - start.QuadPart) * 1000000)/frequency.QuadPart);

           有用的連結：http://dev.csdn.net/develop/article/41/41104.shtm

                                   http://dev.csdn.net/article/74/74169.shtm