關於GetTickCount和QueryPerformanceCounter的精度區別

其實差別不大，寫了兩個類來測試：

 

class TimeCounter

{

private:

DWORD start;

public:

TimeCounter() {Start();}

void Start(){start = GetTickCount(); }

DWORD Now() 

{ 

DWORD end = GetTickCount();

return (end - start); // return miliseconds

}

};

 

 

class HighResolutionTimeCounter

{

LARGE_INTEGER start;

LARGE_INTEGER freq;

public:

HighResolutionTimeCounter() { QueryPerformanceFrequency(&freq); Start();}

void Start() { QueryPerformanceCounter(&start); }

__int64 Now() //  return miliseconds

{ 

LARGE_INTEGER end = { 0 };

QueryPerformanceCounter(&end);

return (end.QuadPart - start.QuadPart)*1000 / freq.QuadPart;

}

};

 

測試代碼 ：

TimeCounter tc;

HighResolutionTimeCounter hrtc;

 

Sleep(10*1000);

 

cout << tc.Now() << endl;

cout << hrtc.Now() <<endl;

 

最後得到的結果的區別是很小的。