精确计时(QueryPerformanceFrequency)

 LARGE_INTEGER litmp;    //The LARGE_INTEGER structure is used to represent a 64-bit signed integer value.
    LONGLONG QPart1,QPart2; // 声明2个长整型
    double dfMinutes,dfFreq,dfTim;//声明2个双精度类型
    QueryPerformanceFrequency(&litmp);

    dfFreq=(double)litmp.QuadPart;
    QueryPerformanceCounter(&litmp);

    QPart1=litmp.QuadPart;
    Sleep(100);
    QueryPerformanceCounter(&litmp);//获得中止的数值
    QPart2=litmp.QuadPart;
    dfMinutes=(double)(QPart2-QPart1);
    dfTim=dfMinutes/dfFreq;
    Edit1->Text=FloatToStr(dfTim);