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Re: what is the best way to get microseconds of time on Windows in C or C++ ?

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On 11/14/2022 7:36 PM, Keith Thompson wrote:
> Lynn McGuire <lynnmcguire5@gmail.com> writes:
>> On 11/4/2022 8:44 AM, Scott Lurndal wrote:
>>> Lynn McGuire <lynnmcguire5@gmail.com> writes:
>>>> What is the best way to get microseconds of time on Windows in C or C++
>>>> ?  I am currently using the following code to get the current time:
>>>>
>>>> 	std::time_t t = std::time (0);   // get time now
>>>> 	std::tm * now = std::localtime ( & t);
>>>> 	integer iyear = now -> tm_year + 1900;
>>>> 	integer imonth = now -> tm_mon + 1;
>>>> 	integer iday = now -> tm_mday;
>>>> 	integer ihour = now -> tm_hour;
>>>> 	integer imin = now -> tm_min;
>>>> 	integer isec = now -> tm_sec;
>>>> 	integer ihund = 0;
>>>>
>>>> Thanks,
>>>> Lynn
>>> First answer here:
>>> https://stackoverflow.com/questions/10905892/equivalent-of-gettimeday-for-windows
>>
>> "Nowadys I would use the following for gettimeofday() on Windows,
>> which is using GetSystemTimePreciseAsFileTime() if compiled for
>> Windows 8 or higher and GetSystemTimeAsFileTime() otherwise:"
>>
>> I used the gettimeofday function.  Works well !
> 
> Be aware that POSIX says gettimeofday() is obsolescent, and recommends
> clock_gettime() instead.

This works fine for me:

	//  from:
	// 
https://stackoverflow.com/questions/10905892/equivalent-of-gettimeday-for-windows

struct timezone {
	int tz_minuteswest;
	int tz_dsttime;
};

int mygettimeofday (struct timeval *tv, struct timezone *tz)
{
	if (tv) {
		FILETIME               filetime; /* 64-bit value representing the 
number of 100-nanosecond intervals since January 1, 1601 00:00 UTC */
		ULARGE_INTEGER         x;
		ULONGLONG              usec;
		static const ULONGLONG epoch_offset_us = 11644473600000000ULL; /* 
microseconds betweeen Jan 1,1601 and Jan 1,1970 */

#if _WIN32_WINNT >= _WIN32_WINNT_WIN8
		GetSystemTimePreciseAsFileTime ( & filetime);
#else
		GetSystemTimeAsFileTime ( & filetime);
#endif
		x.LowPart =  filetime.dwLowDateTime;
		x.HighPart = filetime.dwHighDateTime;
		usec = x.QuadPart / 10  -  epoch_offset_us;
		tv->tv_sec  = (time_t) (usec / 1000000ULL);
		tv->tv_usec = (long) (usec % 1000000ULL);
	}
	if (tz) {
		TIME_ZONE_INFORMATION timezone;
		GetTimeZoneInformation(&timezone);
		tz->tz_minuteswest = timezone.Bias;
		tz->tz_dsttime = 0;
	}
	return 0;
}

Thanks,
Lynn

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Thread

what is the best way to get microseconds of time on Windows in C or C++ ? Lynn McGuire <lynnmcguire5@gmail.com> - 2022-11-03 20:14 -0500
  Re: what is the best way to get microseconds of time on Windows in C or C++ ? DFS <nospam@dfs.com> - 2022-11-03 21:51 -0400
    Re: what is the best way to get microseconds of time on Windows in C or C++ ? Lynn McGuire <lynnmcguire5@gmail.com> - 2022-11-04 00:06 -0500
      Re: what is the best way to get microseconds of time on Windows in C or C++ ? Christian Gollwitzer <auriocus@gmx.de> - 2022-11-04 08:03 +0100
        Re: what is the best way to get microseconds of time on Windows in C or C++ ? Lynn McGuire <lynnmcguire5@gmail.com> - 2022-11-04 14:32 -0500
      Re: what is the best way to get microseconds of time on Windows in C or C++ ? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2022-11-04 09:07 -0700
        Re: what is the best way to get microseconds of time on Windows in C or C++ ? Lynn McGuire <lynnmcguire5@gmail.com> - 2022-11-04 14:33 -0500
      Re: what is the best way to get microseconds of time on Windows in C or C++ ? Opus <ifonly@youknew.org> - 2022-11-06 20:53 +0100
  Re: what is the best way to get microseconds of time on Windows in C or C++ ? Juha Nieminen <nospam@thanks.invalid> - 2022-11-04 07:35 +0000
    Re: what is the best way to get microseconds of time on Windows in C or C++ ? Lynn McGuire <lynnmcguire5@gmail.com> - 2022-11-04 14:24 -0500
      Re: what is the best way to get microseconds of time on Windows in C or C++ ? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2022-11-04 19:50 +0000
        Re: what is the best way to get microseconds of time on Windows in C or C++ ? Lynn McGuire <lynnmcguire5@gmail.com> - 2022-11-04 15:16 -0500
      Re: what is the best way to get microseconds of time on Windows in C or C++ ? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2022-11-04 15:05 -0700
        Re: what is the best way to get microseconds of time on Windows in C or C++ ? Lynn McGuire <lynnmcguire5@gmail.com> - 2022-11-04 17:35 -0500
          Re: what is the best way to get microseconds of time on Windows in C or C++ ? "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2022-11-04 15:56 -0700
          Re: what is the best way to get microseconds of time on Windows in C or C++ ? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2022-11-04 16:15 -0700
  Re: what is the best way to get microseconds of time on Windows in C or C++ ? scott@slp53.sl.home (Scott Lurndal) - 2022-11-04 13:44 +0000
    Re: what is the best way to get microseconds of time on Windows in C or C++ ? Lynn McGuire <lynnmcguire5@gmail.com> - 2022-11-04 14:34 -0500
    Re: what is the best way to get microseconds of time on Windows in C or C++ ? Lynn McGuire <lynnmcguire5@gmail.com> - 2022-11-14 16:58 -0600
      Re: what is the best way to get microseconds of time on Windows in C or C++ ? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2022-11-14 17:36 -0800
        Re: what is the best way to get microseconds of time on Windows in C or C++ ? Lynn McGuire <lynnmcguire5@gmail.com> - 2022-11-15 17:26 -0600
          Re: what is the best way to get microseconds of time on Windows in C or C++ ? Andreas <nospam@gmx.de> - 2022-11-16 13:15 +0100
  Re: what is the best way to get microseconds of time on Windows in C or C++ ? Bonita Montero <Bonita.Montero@gmail.com> - 2022-11-04 20:49 +0100
    Re: what is the best way to get microseconds of time on Windows in C or C++ ? Bart <bc@freeuk.com> - 2022-11-04 22:31 +0000
      Re: what is the best way to get microseconds of time on Windows in C or C++ ? Bonita Montero <Bonita.Montero@gmail.com> - 2022-11-05 06:40 +0100
  Re: what is the best way to get microseconds of time on Windows in C or C++ ? Manu Raju <MR@invalid.invalid> - 2022-11-20 21:30 +0000

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