计算代码运行的时间

#include "stdafx.h"
#include "windows.h"

int _tmain(int argc, _TCHAR* argv[])
{
    LARGE_INTEGER nFreq;
    LARGE_INTEGER nBeginTime;
    LARGE_INTEGER nEndTime;
    double time;

    QueryPerformanceFrequency(&nFreq);
    QueryPerformanceCounter(&nBeginTime);

    Sleep(1000);

    QueryPerformanceCounter(&nEndTime);
    time = (double)(nEndTime.QuadPart - nBeginTime.QuadPart) / (double)nFreq.QuadPart;
    printf("%f\n", time);

    return 0;
}