MFC 高精度計時器

::GetTickCount誤差18ms，所以不適合用於計算時間很短的程序，尤其是算法分析

#include <windows.h>

// 高精度計時器
class HpTimer
{
public:
    HpTimer()
    {
        QueryPerformanceFrequency(&cpuFrequency);
    }

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

    // 秒， 乘以1000就是毫秒
    double Elapse()
    {
        LARGE_INTEGER end;
        QueryPerformanceCounter(&end);
        double elaspe;
        elaspe = ((double)end.QuadPart - (double)start.QuadPart) / (double)cpuFrequency.QuadPart;
        return elaspe;
    }

private:
    LARGE_INTEGER start;
    LARGE_INTEGER cpuFrequency;
};