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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 11/4/2022 5:05 PM, Keith Thompson wrote:
> Lynn McGuire <lynnmcguire5@gmail.com> writes:
>> On 11/4/2022 2:35 AM, Juha Nieminen wrote:
>>> In comp.lang.c++ Lynn McGuire <lynnmcguire5@gmail.com> wrote:
>>>> What is the best way to get microseconds of time on Windows in C or C++
>>> It's a bit unclear whether you mean "time in microseconds units" or
>>> "time
>>> at the microseconds resolution".
>>> Because the latter may not be even possible (portable or not). Just
>>> because
>>> some time function returns time "in microseconds" that doesn't mean that it
>>> uses microsecond resolution (in other words, the value it returns may well
>>> change at longer intervals than every microsecond; probably *significantly*
>>> longer intervals).
>>> It is possible to get some kind of timing at the CPU clock cycle
>>> interval
>>> (in most modern CPUs, at least), which is about as accurate as you can
>>> possibly get, but I don't know if there are eg. some system functions that
>>> will return elapsed clock cycles converted into the equivalent amount of
>>> microseconds.
>>
>> Get time at the microseconds resolution.   My calculation engine
>> creates a bunch of temporary files and I use the time to create unique
>> names for those temporary files.  Seconds should be good enough for
>> uniqueness but I like adding microseconds as a guarantee.  Something
>> like
>>     uniquac1.out.009.20181972.20220912
> 
> An alternative is to keep a counter, incremented for each generated file
> name, and append it to the file name, perhaps resetting to 0 when the
> seconds count advances.  If your only requirement is uniqueness, that
> should be good enough.
> 
> Digression: I remember an implementation of gettimeofday() that did
> something like that (on SunOS, maybe?).  The system clock had a
> resolution of 0.01 second, so the value of tv_usec on successive calls
> might be:
>      420000
>      420001
>      420002
>      430000
>      430001
>      430002
>      ...
> I don't remember whether the implicit counter was per-process or
> system-wide.

The problem is multiple instances of the same program creating the same 
name files.

Lynn

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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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