如何精确计算时间到微秒级

 一、

windows系统中取得微妙和毫秒级的时间

2008-04-23 11:57

windows系统中得到精确到微妙的时间(通过cpu频率计算) #include <windows.h> #include <iostream> (取得cpu频率) LARGE_INTEGER t1,t2,feq; QueryPerformanceFrequency(&feq);//每秒跳动次数 QueryPerformanceCounter(&t1);//测前跳动次数 for(int i = 0;i<10000;i++); QueryPerformanceCounter(&t2);//测后跳动次数 double d=((double)t2.QuadPart-(double)t1.QuadPart)/((double)feq.QuadPart);//时间差秒 std::cout<<d<<std::endl; windows系统中得到精确到毫妙的时间 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、

我最初用的函数是timeGetTime（），该函数只能精确到ms，具体用法如下

         #include <mmsystem.h>

         DOWD begin, end;

         begin = timeGetTime();

        //你要计算的程序片断

         end = timeGetTime();

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

           最后在你的工程里面设置linker-input-Additional Dependencies 加上Winmm.lib

           如果要显示微妙级的就不够用了，可以采用系统的计数器来实现。

           LARGE_INTEGER frequency ;
           QueryPerformanceFrequency(&frequency );
   
            LARGE_INTEGER start, end;
            QueryPerformanceCounter(&start);
            //你要计算的程序片断  
 
           QueryPerformanceCounter(&end);

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

           有用的链接：http://dev.csdn.net/develop/article/41/41104.shtm

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