检测代码运行效率 GetTickCount()的使用

   调试程序的时很多时候都想知道自己写的程序运行的效率，也就是说因该得到这段程序运行的时间，我下面介绍这个函数就可以完成这个功能，她就是：GetTickCount()

   下面是MSDN上的解释：

   GetTickCount

     The GetTickCount function retrieves the number of milliseconds that have elapsed since the system was started. It is limited to the resolution of the system timer. To obtain the system timer resolution, use the function.

DWORD GetTickCount(VOID);

Parameters

This function has no parameters.

Return Values

The return value is the number of milliseconds that have elapsed since the system was started.

Remarks

The elapsed time is stored as a DWORD value. Therefore, the time will wrap around to zero if the system is run continuously for 49.7 days.

If you need a higher resolution timer, use a or a .

Windows NT/2000/XP: To obtain the time elapsed since the computer was started, retrieve the System Up Time counter in the performance data in the registry key HKEY_PERFORMANCE_DATA. The value returned is an 8-byte value. For more information, see .

Example Code

The following example demonstrates how to handle timer wrap around.

DWORD dwStart = GetTickCount();

// Stop if this has taken too long
if( GetTickCount() - dwStart >= TIMELIMIT )
    Cancel();

这个函数是取得程序运行到现在的时间，这样在检测代码的前后各运行一次这个函数，两次的差就是程序运行的大概的时间了。例如：

DWORD dwStart;
DWORD dwEnd;
dwStart = GetTickCount();

//要检测的代码

dwEnd = GetTickCount();
CString s ;
s.Format( "%d", dwEnd- dwStart ) ;
AfxMessageBox( s ) ;

这个函数也可以用作定时，例如：

＃i nclude 
＃i nclude 
void main() 
{
     DWORD dwLast;
     DWORD dwCurrent;
     DWORD dwInterval = 1000;
 
dwLast = GetTickCount();
     int i = 0;
     while(true)
     {
         dwCurrent = GetTickCount();
         if( dwCurrent - dwLast < dwInterval )
              continue;
         //your code to be executed when interval is elapsed
         printf("dwLast,dwCurrent,diff:%d,%d,%d\n",dwLast,dwCurrent,dwCurrent-dwLast);
         //your code to determine when to break
         if( i > 10 ) break;
         i++;
         dwLast = dwCurrent;
     }
   getchar();   
   return