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Re: Cookies in boxes - algorithmic challenge

From Tim Rentsch <tr.17687@z991.linuxsc.com>
Newsgroups comp.lang.c
Subject Re: Cookies in boxes - algorithmic challenge
Date 2026-04-10 22:41 -0700
Organization A noiseless patient Spider
Message-ID <861pgmawaz.fsf@linuxsc.com> (permalink)
References <20260401163447.000052de@yahoo.com> <86tstlwjak.fsf@linuxsc.com> <20260408222330.00005cf8@yahoo.com> <865x5zbg10.fsf@linuxsc.com> <20260410122314.000063c5@yahoo.com>

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Michael S <already5chosen@yahoo.com> writes:
> Tim Rentsch <tr.17687@z991.linuxsc.com> wrote:
>> Michael S <already5chosen@yahoo.com> writes:
>>> Tim Rentsch <tr.17687@z991.linuxsc.com> wrote:
[...]
>>>> I ran into trouble when I tried to work within the posted framework
>>>> to drive a solver.  The difficulties were of several kinds.  The
>>>> code didn't compile in my standard compilation environment, which
>>>> is roughly this (the c99 might be c11 but that made no difference):
>>>>
>>>>     gcc -x c -std=c99 -pedantic ...
>>>
>>> What were the problems?
>>> My gcc 14.2.0 on msys2 produces no warnings or errors with above
>>> flags.
>>
>> These source lines
>>
>>     struct timespec t0;
>>     clock_gettime(CLOCK_MONOTONIC, &t0);
>>
>> produced these diagnostics
>>
>>   tb.c:134:21: error: storage size of 't0' isn't known
>>   tb.c:135:5: warning: implicit declaration of function
>> 'clock_gettime' [...] tb.c:135:19: error: 'CLOCK_MONOTONIC'
>> undeclared (first use in this function)
>>
>> under -std=c99.  Apparently the first diagnostic, about
>> struct timespec, is fixed under -std=c11.  It wasn't hard
>> to fix these, but it was irksome.
>
> Sounds like under Linux and with -std=c99 flag function clock_gettime()
> and related structures and constants are not declared/defined by default
> in time.h.

Yes, gcc follows the ISO standard exactly, and does not define
symbols like clock_gettime, because the C standard does not
allow conforming impementations to do so.

> Man page suggests magic pixie dust:
>
> #define _XOPEN_SOURCE 600
> #include <time.h>
> #include <unistd.h>

It is my practice not to mix ISO-conformant and non-ISO-conformant
code in the same translation unit.  It wasn't hard to find the
necessary tweak for a separate source file used to get the
current time:

    #define _POSIX_C_SOURCE 199309L
    #include <time.h>

after which both the 'struct timespec' and 'clock_gettime()' were
quite okay.  I packaged the time in a way so it could get across
the function call interface and back to the main program.

> If you ask why I used clock_gettime() instead of C standard
> timespec_get() then the answer is that on Windows, eps. on older
> versions like Win7 and WS2008 (which I prefer over newer stuff for
> reasons unrelated to quality of C RTL), precision of timespec_get() is
> poor.  clock_gettime(CLOCK_MONOTONIC,) is much better.

Makes sense.

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Cookies in boxes - algorithmic challenge Michael S <already5chosen@yahoo.com> - 2026-04-01 16:34 +0300
  Re: Cookies in boxes - algorithmic challenge DFS <nospam@dfs.com> - 2026-04-01 10:02 -0400
    Re: Cookies in boxes - algorithmic challenge Michael S <already5chosen@yahoo.com> - 2026-04-01 17:15 +0300
      Re: Cookies in boxes - algorithmic challenge DFS <nospam@dfs.com> - 2026-04-01 10:28 -0400
        Re: Cookies in boxes - algorithmic challenge Michael S <already5chosen@yahoo.com> - 2026-04-01 17:58 +0300
  Re: Cookies in boxes - algorithmic challenge Bart <bc@freeuk.com> - 2026-04-01 15:20 +0100
    Re: Cookies in boxes - algorithmic challenge Michael S <already5chosen@yahoo.com> - 2026-04-01 17:56 +0300
      Re: Cookies in boxes - algorithmic challenge Bart <bc@freeuk.com> - 2026-04-01 19:50 +0100
        Re: Cookies in boxes - algorithmic challenge DFS <nospam@dfs.com> - 2026-04-01 15:56 -0400
          Re: Cookies in boxes - algorithmic challenge Bart <bc@freeuk.com> - 2026-04-01 23:33 +0100
        Re: Cookies in boxes - algorithmic challenge Richard Harnden <richard.nospam@gmail.invalid> - 2026-04-04 07:43 +0100
          Re: Cookies in boxes - algorithmic challenge Bart <bc@freeuk.com> - 2026-04-04 11:54 +0100
  Re: Cookies in boxes - algorithmic challenge DFS <nospam@dfs.com> - 2026-04-01 15:24 -0400
  Re: Cookies in boxes - algorithmic challenge DFS <nospam@dfs.com> - 2026-04-01 17:24 -0400
    Re: Cookies in boxes - algorithmic challenge Mike Terry <news.dead.person.stones@darjeeling.plus.com> - 2026-04-02 16:25 +0100
      Re: Cookies in boxes - algorithmic challenge Bart <bc@freeuk.com> - 2026-04-02 17:10 +0100
        Re: Cookies in boxes - algorithmic challenge Michael S <already5chosen@yahoo.com> - 2026-04-02 22:19 +0300
      Re: Cookies in boxes - algorithmic challenge DFS <nospam@dfs.com> - 2026-04-02 13:03 -0400
        Re: Cookies in boxes - algorithmic challenge Richard Harnden <richard.nospam@gmail.invalid> - 2026-04-02 18:52 +0100
        Re: Cookies in boxes - algorithmic challenge Bart <bc@freeuk.com> - 2026-04-02 19:50 +0100
          Re: Cookies in boxes - algorithmic challenge Michael S <already5chosen@yahoo.com> - 2026-04-02 22:24 +0300
        Re: Cookies in boxes - algorithmic challenge Mike Terry <news.dead.person.stones@darjeeling.plus.com> - 2026-04-02 20:13 +0100
          Re: Cookies in boxes - algorithmic challenge Michael S <already5chosen@yahoo.com> - 2026-04-02 22:36 +0300
      Re: Cookies in boxes - algorithmic challenge Michael S <already5chosen@yahoo.com> - 2026-04-02 22:14 +0300
    Re: Cookies in boxes - algorithmic challenge Michael S <already5chosen@yahoo.com> - 2026-04-02 22:10 +0300
      Re: Cookies in boxes - algorithmic challenge Tristan Wibberley <tristan.wibberley+netnews2@alumni.manchester.ac.uk> - 2026-04-06 22:36 +0100
        Re: Cookies in boxes - algorithmic challenge Tim Rentsch <tr.17687@z991.linuxsc.com> - 2026-04-06 15:42 -0700
        Re: Cookies in boxes - algorithmic challenge Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2026-04-06 15:44 -0700
  Re: Cookies in boxes - algorithmic challenge DFS <nospam@dfs.com> - 2026-04-04 13:33 -0400
    Re: Cookies in boxes - algorithmic challenge Michael S <already5chosen@yahoo.com> - 2026-04-04 21:03 +0300
      Re: Cookies in boxes - algorithmic challenge DFS <nospam@dfs.com> - 2026-04-04 14:19 -0400
      Re: Cookies in boxes - algorithmic challenge Bart <bc@freeuk.com> - 2026-04-04 20:22 +0100
        Re: Cookies in boxes - algorithmic challenge Michael S <already5chosen@yahoo.com> - 2026-04-04 22:40 +0300
  Re: Cookies in boxes - algorithmic challenge Tim Rentsch <tr.17687@z991.linuxsc.com> - 2026-04-04 17:08 -0700
  Re: Cookies in boxes - algorithmic challenge Tim Rentsch <tr.17687@z991.linuxsc.com> - 2026-04-08 08:42 -0700
    Re: Cookies in boxes - algorithmic challenge Michael S <already5chosen@yahoo.com> - 2026-04-08 22:23 +0300
      Re: Cookies in boxes - algorithmic challenge Tim Rentsch <tr.17687@z991.linuxsc.com> - 2026-04-09 21:22 -0700
        Re: Cookies in boxes - algorithmic challenge Michael S <already5chosen@yahoo.com> - 2026-04-10 12:23 +0300
          Re: Cookies in boxes - algorithmic challenge Tim Rentsch <tr.17687@z991.linuxsc.com> - 2026-04-10 22:41 -0700
        Re: Cookies in boxes - algorithmic challenge Michael S <already5chosen@yahoo.com> - 2026-04-10 16:16 +0300
          Re: Cookies in boxes - algorithmic challenge Tim Rentsch <tr.17687@z991.linuxsc.com> - 2026-04-11 04:27 -0700
        Re: Cookies in boxes - algorithmic challenge Michael S <already5chosen@yahoo.com> - 2026-04-11 22:56 +0300
          Re: Cookies in boxes - algorithmic challenge Tim Rentsch <tr.17687@z991.linuxsc.com> - 2026-04-11 15:57 -0700
            Re: Cookies in boxes - algorithmic challenge Michael S <already5chosen@yahoo.com> - 2026-04-12 02:15 +0300
            Re: Cookies in boxes - algorithmic challenge Michael S <already5chosen@yahoo.com> - 2026-04-13 02:03 +0300
            Re: Cookies in boxes - algorithmic challenge Michael S <already5chosen@yahoo.com> - 2026-04-13 17:11 +0300
              Re: Cookies in boxes - algorithmic challenge Tim Rentsch <tr.17687@z991.linuxsc.com> - 2026-04-16 23:52 -0700
                Re: Cookies in boxes - algorithmic challenge Michael S <already5chosen@yahoo.com> - 2026-04-17 14:44 +0300
                Re: Cookies in boxes - algorithmic challenge Tim Rentsch <tr.17687@z991.linuxsc.com> - 2026-04-17 07:40 -0700
                Re: Cookies in boxes - algorithmic challenge Michael S <already5chosen@yahoo.com> - 2026-04-17 18:30 +0300
                Re: Cookies in boxes - algorithmic challenge Michael S <already5chosen@yahoo.com> - 2026-04-20 00:43 +0300
                Re: Cookies in boxes - algorithmic challenge Michael S <already5chosen@yahoo.com> - 2026-04-21 20:37 +0300
                Re: Cookies in boxes - algorithmic challenge Tim Rentsch <tr.17687@z991.linuxsc.com> - 2026-04-21 18:22 -0700
                Re: Cookies in boxes - algorithmic challenge Michael S <already5chosen@yahoo.com> - 2026-04-22 12:05 +0300
    Re: Cookies in boxes - algorithmic challenge Michael S <already5chosen@yahoo.com> - 2026-04-15 02:15 +0300
      Re: Cookies in boxes - algorithmic challenge Tim Rentsch <tr.17687@z991.linuxsc.com> - 2026-04-16 02:57 -0700
        Re: Cookies in boxes - algorithmic challenge Michael S <already5chosen@yahoo.com> - 2026-04-17 17:04 +0300
  Re: Cookies in boxes - algorithmic challenge Michael S <already5chosen@yahoo.com> - 2026-04-08 23:45 +0300
    Re: Cookies in boxes - algorithmic challenge Tim Rentsch <tr.17687@z991.linuxsc.com> - 2026-04-09 16:37 -0700
      Re: Cookies in boxes - algorithmic challenge Michael S <already5chosen@yahoo.com> - 2026-04-10 17:02 +0300
        Re: Cookies in boxes - algorithmic challenge Tim Rentsch <tr.17687@z991.linuxsc.com> - 2026-04-11 03:45 -0700
  Re: Cookies in boxes - algorithmic challenge Michael S <already5chosen@yahoo.com> - 2026-04-09 00:01 +0300
    Re: Cookies in boxes - algorithmic challenge Tim Rentsch <tr.17687@z991.linuxsc.com> - 2026-04-09 17:07 -0700
      Re: Cookies in boxes - algorithmic challenge Michael S <already5chosen@yahoo.com> - 2026-04-10 18:06 +0300
        Re: Cookies in boxes - algorithmic challenge Tim Rentsch <tr.17687@z991.linuxsc.com> - 2026-04-11 04:31 -0700
        Re: Cookies in boxes - algorithmic challenge Tim Rentsch <tr.17687@z991.linuxsc.com> - 2026-04-16 03:22 -0700
  Re: Cookies in boxes - algorithmic challenge Bonita Montero <Bonita.Montero@gmail.com> - 2026-04-17 17:58 +0200
    Re: Cookies in boxes - algorithmic challenge Bonita Montero <Bonita.Montero@gmail.com> - 2026-04-17 18:08 +0200
    Re: Cookies in boxes - algorithmic challenge Bart <bc@freeuk.com> - 2026-04-17 17:47 +0100
      Re: Cookies in boxes - algorithmic challenge Bonita Montero <Bonita.Montero@gmail.com> - 2026-04-17 19:24 +0200
    Re: Cookies in boxes - algorithmic challenge scott@slp53.sl.home (Scott Lurndal) - 2026-04-17 19:58 +0000
      Re: Cookies in boxes - algorithmic challenge Bonita Montero <Bonita.Montero@gmail.com> - 2026-04-18 05:52 +0200
        Re: Cookies in boxes - algorithmic challenge Bart <bc@freeuk.com> - 2026-04-18 11:53 +0100
          Re: Cookies in boxes - algorithmic challenge Bart <bc@freeuk.com> - 2026-04-18 12:04 +0100
        Re: Cookies in boxes - algorithmic challenge Michael S <already5chosen@yahoo.com> - 2026-04-18 20:35 +0300
  Re: Cookies in boxes - algorithmic challenge Bonita Montero <Bonita.Montero@gmail.com> - 2026-04-17 19:52 +0200
    Re: Cookies in boxes - algorithmic challenge Bonita Montero <Bonita.Montero@gmail.com> - 2026-04-17 20:17 +0200

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