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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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Lynn McGuire <lynnmcguire5@gmail.com> writes:
> 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.

You could incorporate the process id into the file name.

There's no truly portable way to do that, but one solution for POSIX and
another for Windows is likely to be good enough.

-- 
Keith Thompson (The_Other_Keith) Keith.S.Thompson+u@gmail.com
Working, but not speaking, for XCOM Labs
void Void(void) { Void(); } /* The recursive call of the void */

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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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