Visual C++跑表

Question

我想知道测量 C++ 中某些代码的执行时间的最佳方法是什么。是否有内置的秒表（.Net）类似类？我正在VS2010上开发C++。我如何（如果）在我的 C++ 项目中使用 .Net 库？先感谢您。

Answer 1

AFAIK C++ 还没有像 .NET 中的 Stopwatch 这样的标准类。

http://cplus.about.com/od/howtodothingsi2/a/timing.htm 是windows平台上高分辨率定时器的示例。

此类计时器的独立于平台的实现是： http://www.boost.org/ libs/timer/doc/index.html

HTH

Answer 2

您可以考虑http://code.google.com/p/cpp-stopwatch，它采用纯 C++ 编写，没有依赖项，并附带方便的 Visual Studio 解决方案。哦，我写的。

Answer 3

您可以使用 QueryPerformanceCounter 在“分析”某些代码时获得更好的时机（它并不完美，但应该足以让您入门）。

BOOL WINAPI QueryPerformanceCounter( __out  LARGE_INTEGER *lpPerformanceCount );

http://msdn.microsoft。 com/en-us/library/windows/desktop/ms644904(v=vs.85).aspx。

Answer 4

就其价值而言，这里是一个 Windows 实现（与 .NET 非常相似）：

class Stopwatch
{
    LARGE_INTEGER _startTime;
    LARGE_INTEGER _frequency;

public:
    Stopwatch(bool start = false) :_startTime({ 0 })
    {
        QueryPerformanceFrequency(&_frequency);
        if (start)
        {
            Start();
        }
    }

    LONGLONG GetStartTime() { return _startTime.QuadPart; }
    bool IsStarted() { return _startTime.QuadPart; }
    bool IsStopped() { return !IsStarted(); }

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

    void Stop()
    {
        ZeroMemory(&_startTime, sizeof(LARGE_INTEGER));
    }

    static LONGLONG GetFrequency()
    {
        LARGE_INTEGER li;
        QueryPerformanceFrequency(&li);
        return li.QuadPart;
    }

    static LONGLONG GetTicks()
    {
        LARGE_INTEGER endingTime;
        QueryPerformanceCounter(&endingTime);
        return endingTime.QuadPart;
    }

    LONGLONG GetElapsedTicks(bool restart = false)
    {
        LARGE_INTEGER endingTime;
        QueryPerformanceCounter(&endingTime);
        auto qp = endingTime.QuadPart - _startTime.QuadPart;
        if (restart)
        {
            Start();
        }
        return qp;
    }

    LONGLONG GetElapsed100NanoSeconds(bool restart = false)
    {
        LARGE_INTEGER endingTime;
        QueryPerformanceCounter(&endingTime);

        LARGE_INTEGER elapsed100NanoSeconds{};
        elapsed100NanoSeconds.QuadPart = endingTime.QuadPart - _startTime.QuadPart;
        elapsed100NanoSeconds.QuadPart *= 10000000;
        elapsed100NanoSeconds.QuadPart /= _frequency.QuadPart;
        if (restart)
        {
            Start();
        }
        return elapsed100NanoSeconds.QuadPart;
    }

    LONGLONG GetElapsedMicroseconds(bool restart = false)
    {
        LARGE_INTEGER endingTime;
        QueryPerformanceCounter(&endingTime);

        LARGE_INTEGER elapsedMicroSeconds{};
        elapsedMicroSeconds.QuadPart = endingTime.QuadPart - _startTime.QuadPart;
        elapsedMicroSeconds.QuadPart *= 1000000;
        elapsedMicroSeconds.QuadPart /= _frequency.QuadPart;
        if (restart)
        {
            Start();
        }
        return elapsedMicroSeconds.QuadPart;
    }

    LONGLONG GetElapsedMilliseconds(bool restart = false)
    {
        LARGE_INTEGER endingTime;
        QueryPerformanceCounter(&endingTime);

        LARGE_INTEGER elapsedMilliSeconds{};
        elapsedMilliSeconds.QuadPart = endingTime.QuadPart - _startTime.QuadPart;
        elapsedMilliSeconds.QuadPart *= 1000;
        elapsedMilliSeconds.QuadPart /= _frequency.QuadPart;
        if (restart)
        {
            Start();
        }
        return elapsedMilliSeconds.QuadPart;
    }

    LONGLONG GetElapsedSeconds(bool restart = false)
    {
        LARGE_INTEGER endingTime;
        QueryPerformanceCounter(&endingTime);

        LARGE_INTEGER elapsedSeconds{};
        elapsedSeconds.QuadPart = endingTime.QuadPart - _startTime.QuadPart;
        elapsedSeconds.QuadPart /= _frequency.QuadPart;
        if (restart)
        {
            Start();
        }
        return elapsedSeconds.QuadPart;
    }
};