获得时间点，微秒精度 [英] Getting time point with microseconds precision

问题描述

我需要以微秒的精度检索当前时间点。时间点可以是相对于任何固定日期。

I need to retrieve the current time point with a precision of microseconds. The time point can be relative to any fixed date.

如何实现？对于工作政策，我真的不应该使用 boost 或任何其他库。

How can it be achieved? For job policy, I really should't use boost or any other lib.

多平台应用程序，在Linux下，我可以使用C ++ 11 system_clock :: now（）。time_since_epoch（），但在Windows下我使用VS2010， code> std :: chrono 库。

I'm working at a multiplatform application and under Linux, I can use C++11 system_clock::now().time_since_epoch(), but under Windows I work with VS2010, so I have no std::chrono library.

我看到了 RtlTimeToSecondsSince1970 函数，但其​​分辨率是第二个。

I've seen the RtlTimeToSecondsSince1970 function, but its resolution is a second.

推荐答案

计时器和计时是一个棘手的问题，平台实现不是很划算。所以我推荐一个适当的 #ifdef 的Windows的特定版本。

Timers and timing is a tricky enough subject that In my opinion current cross platform implementations are not quite up to scratch. So I'd recommend a specific version for windows with appropriate #ifdef's. See other answers if you want a cross-platform version.

如果您已经/想使用windows特定的调用，则 GetSystemTimeAsFileTime （或在Windows 8 GetSystemTimePreciseAsFileTime ）是获取UTC时间的最佳调用， QueryPerformanceCounter 有利于高分辨率时间戳。它将自1601年1月1日起的 100纳秒间隔数量返回到FILETIME结构中。

If you've got to/want to use a windows specific call then GetSystemTimeAsFileTime (or on windows 8 GetSystemTimePreciseAsFileTime) are the best calls for getting UTC time and QueryPerformanceCounter is good for high resolution timestamps. It gives back the number of 100-nanosecond intervals since January 1, 1601 UTC into a FILETIME structure.

这篇精细的文章进入了测量的细节计时器和时间戳，非常值得一读。

This fine article goes into the gory details of measuring timers and timestamps in windows and is well worth a read.

编辑：转换一个FILETIME给我们，你需要通过ULARGE_INTEGER。

Converting a FILETIME to us, you need to go via a ULARGE_INTEGER.

FILETIME ft;
GetSystemTimeAsFileTime(&ft);
ULARGE_INTEGER li;
li.LowPart = ft.dwLowDateTime;
li.HighPart = ft.dwHighDateTime;
unsigned long long valueAsHns = li.QuadPart;
unsigned long long valueAsUs = valueAsHns/10;

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