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Re: srand(0)

From Keith Thompson <Keith.S.Thompson+u@gmail.com>
Newsgroups comp.lang.c
Subject Re: srand(0)
Date 2025-12-23 16:30 -0800
Organization None to speak of
Message-ID <87h5tg90x3.fsf@example.invalid> (permalink)
References (6 earlier) <10ices7$25ihi$5@dont-email.me> <20251223111855.000035ba@yahoo.com> <10idosf$25ihh$4@dont-email.me> <20251223135031.000000b3@yahoo.com> <10if8lm$2sora$3@dont-email.me>

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James Kuyper <jameskuyper@alumni.caltech.edu> writes:
> On 2025-12-23 06:50, Michael S wrote:
>> On Tue, 23 Dec 2025 10:54:23 +0100
>> Janis Papanagnou <janis_papanagnou+ng@hotmail.com> wrote:
>> 
>>> On 2025-12-23 10:18, Michael S wrote:
> ...
>>>> MT19937-64 is available out of the box(*) in C++. But not in C,
>>>> unfortunately.  
>>>
>>> This is really strange given that the name ("Mersenne Twister") is
>>> that prominent.
>>>
>>> Looking that up I find at least "C" code for MT19937 in Wikipedia
>>> https://de.wikipedia.org/wiki/Mersenne-Twister
>>> It's based on 32 bit logic it seems; interpreting your "MT19937-64"
>>> I assume you're looking for a 64 bit based version?
>>>
>> 
>> "Available out of the box" in this sentence means "part of standard
>> library".
>
> Citation, please? I can find neither Mersenne nor "MT19937-64" anywhere
> in n5001.pdf, the latest draft version of the C++ standard that I have
> access to, which is dated 2024-12-17.

N5001 29.5.4.3 [rand.eng.mers] "Class template mersenne_twister_engine".

N5001 29.5.6 [rand.predef] "Engines and engine adaptors with predefined
parameters" defines "mt19937" and "mt19937_64".

Its description of the algorithm isn't very detailed, but it
does impose some very specific requirements.  For mt19937:
"Required behavior: The 10000th consecutive invocation of a
default-constructed object of type mt19937 produces the value
4123659995.".  For mt19937_64: "Required behavior: The 10000th
consecutive invocation of a default-constructed object of type
mt19937_64 produces the value 9981545732273789042."

If we're going to discuss this in any more detail (rather than
discussing random numbers in general), I suggest comp.lang.c++.

As already mentioned, there are implementations of mt19937 for C,
but unlike in C++ they aren't part of the standard library.

-- 
Keith Thompson (The_Other_Keith) Keith.S.Thompson+u@gmail.com
void Void(void) { Void(); } /* The recursive call of the void */

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srand(0) Michael Sanders <porkchop@invalid.foo> - 2025-12-22 08:48 +0000
  Re: srand(0) James Kuyper <jameskuyper@alumni.caltech.edu> - 2025-12-22 06:44 -0500
    Re: srand(0) Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2025-12-22 13:18 +0100
      Re: srand(0) James Kuyper <jameskuyper@alumni.caltech.edu> - 2025-12-22 12:13 -0500
        Re: srand(0) Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2025-12-22 18:41 +0100
          Re: srand(0) Michael S <already5chosen@yahoo.com> - 2025-12-22 20:45 +0200
            Re: srand(0) Lawrence D’Oliveiro <ldo@nz.invalid> - 2025-12-22 21:16 +0000
            Re: srand(0) Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2025-12-22 22:19 +0100
            Re: srand(0) Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2025-12-22 22:57 +0100
              Re: srand(0) Michael S <already5chosen@yahoo.com> - 2025-12-23 11:18 +0200
                Re: srand(0) Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2025-12-23 10:54 +0100
                Re: srand(0) Michael S <already5chosen@yahoo.com> - 2025-12-23 13:50 +0200
                Re: srand(0) James Kuyper <jameskuyper@alumni.caltech.edu> - 2025-12-23 18:29 -0500
                Re: srand(0) Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2025-12-23 16:30 -0800
            Re: srand(0) antispam@fricas.org (Waldek Hebisch) - 2025-12-23 17:54 +0000
              Re: srand(0) Michael S <already5chosen@yahoo.com> - 2025-12-24 00:08 +0200
                Re: srand(0) Lawrence D’Oliveiro <ldo@nz.invalid> - 2025-12-24 02:02 +0000
                Re: srand(0) James Kuyper <jameskuyper@alumni.caltech.edu> - 2025-12-23 23:43 -0500
                Re: srand(0) Lawrence D’Oliveiro <ldo@nz.invalid> - 2025-12-24 05:34 +0000
                Re: srand(0) antispam@fricas.org (Waldek Hebisch) - 2025-12-24 09:00 +0000
                Re: srand(0) Michael S <already5chosen@yahoo.com> - 2025-12-24 12:12 +0200
                Article of Melissa O'Nail (Was: srand(0)) Michael S <already5chosen@yahoo.com> - 2025-12-28 02:44 +0200
                Re: Article of Melissa O'Nail antispam@fricas.org (Waldek Hebisch) - 2025-12-28 05:38 +0000
                Re: Article of Melissa O'Nail Michael S <already5chosen@yahoo.com> - 2025-12-28 12:35 +0200
                Re: Article of Melissa O'Nail Michael S <already5chosen@yahoo.com> - 2026-01-05 14:21 +0200
                Re: Article of Melissa O'Nail antispam@fricas.org (Waldek Hebisch) - 2026-01-07 10:51 +0000
                Re: Article of Melissa O'Nail Michael S <already5chosen@yahoo.com> - 2026-01-08 14:03 +0200
                Re: Article of Melissa O'Nail Tim Rentsch <tr.17687@z991.linuxsc.com> - 2026-01-08 09:40 -0800
                Re: srand(0) Tim Rentsch <tr.17687@z991.linuxsc.com> - 2026-01-08 09:26 -0800
                Re: srand(0) "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2025-12-24 13:48 -0800
                Re: srand(0) Tim Rentsch <tr.17687@z991.linuxsc.com> - 2026-01-07 08:41 -0800
                Re: srand(0) Michael S <already5chosen@yahoo.com> - 2026-01-08 01:06 +0200
              Re: srand(0) BGB <cr88192@gmail.com> - 2025-12-24 05:22 -0600
                Re: srand(0) BGB <cr88192@gmail.com> - 2025-12-24 23:09 -0600
                Re: srand(0) Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2025-12-25 09:51 +0100
                Re: srand(0) BGB <cr88192@gmail.com> - 2025-12-25 04:24 -0600
              Re: srand(0) Tim Rentsch <tr.17687@z991.linuxsc.com> - 2026-01-07 07:50 -0800
            Re: srand(0) Tim Rentsch <tr.17687@z991.linuxsc.com> - 2026-01-07 07:46 -0800
              Re: srand(0) Michael S <already5chosen@yahoo.com> - 2026-01-07 18:14 +0200
          Re: srand(0) Kaz Kylheku <046-301-5902@kylheku.com> - 2025-12-22 19:16 +0000
            Re: srand(0) Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2025-12-22 22:35 +0100
      Re: srand(0) Michael Sanders <porkchop@invalid.foo> - 2025-12-23 07:24 +0000
        Re: srand(0) Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2025-12-23 09:59 +0100
          Re: srand(0) Michael Bäuerle <michael.baeuerle@stz-e.de> - 2025-12-23 11:09 +0100
            Re: srand(0) Michael Sanders <porkchop@invalid.foo> - 2025-12-23 14:49 +0000
          Re: srand(0) scott@slp53.sl.home (Scott Lurndal) - 2025-12-23 16:13 +0000
            Re: srand(0) richard@cogsci.ed.ac.uk (Richard Tobin) - 2025-12-23 19:05 +0000
        Re: srand(0) Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2025-12-23 02:16 -0800
          Re: srand(0) Michael Sanders <porkchop@invalid.foo> - 2025-12-23 14:47 +0000
        Re: srand(0) scott@slp53.sl.home (Scott Lurndal) - 2025-12-23 16:08 +0000
          Re: srand(0) Michael Sanders <porkchop@invalid.foo> - 2025-12-24 15:44 +0000
    Re: srand(0) Michael Sanders <porkchop@invalid.foo> - 2025-12-23 07:17 +0000
      Re: srand(0) David Brown <david.brown@hesbynett.no> - 2025-12-23 08:25 +0100
        Re: srand(0) Michael Sanders <porkchop@invalid.foo> - 2025-12-23 14:45 +0000
          Re: srand(0) David Brown <david.brown@hesbynett.no> - 2025-12-23 19:15 +0100
  Re: srand(0) John McCue <jmclnx@gmail.com.invalid> - 2025-12-23 00:39 +0000
    Re: srand(0) Lawrence D’Oliveiro <ldo@nz.invalid> - 2025-12-23 02:17 +0000
      Re: srand(0) Michael Sanders <porkchop@invalid.foo> - 2025-12-23 14:55 +0000
        Re: srand(0) BGB <cr88192@gmail.com> - 2025-12-24 23:35 -0600
          Re: srand(0) Michael Sanders <porkchop@invalid.foo> - 2025-12-26 08:23 +0000
            Re: srand(0) BGB <cr88192@gmail.com> - 2025-12-26 14:48 -0600
              Re: srand(0) BGB <cr88192@gmail.com> - 2025-12-26 15:12 -0600
    Re: srand(0) Ike Naar <ike@sdf.org> - 2025-12-23 06:49 +0000
      Re: srand(0) John McCue <jmclnx@gmail.com.invalid> - 2025-12-23 20:37 +0000
        Re: srand(0) Ike Naar <ike@sdf.org> - 2025-12-24 15:22 +0000
    Re: srand(0) Michael Sanders <porkchop@invalid.foo> - 2025-12-23 07:25 +0000
      Re: srand(0) Lawrence D’Oliveiro <ldo@nz.invalid> - 2025-12-24 06:16 +0000
        Re: srand(0) Michael Sanders <porkchop@invalid.foo> - 2025-12-24 15:21 +0000
          Re: srand(0) Lawrence D’Oliveiro <ldo@nz.invalid> - 2025-12-24 19:00 +0000
            Re: srand(0) BGB <cr88192@gmail.com> - 2025-12-25 03:07 -0600
              Re: srand(0) Lawrence D’Oliveiro <ldo@nz.invalid> - 2025-12-25 19:31 +0000
                Re: srand(0) Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2025-12-25 21:14 +0100
                Re: srand(0) BGB <cr88192@gmail.com> - 2025-12-25 15:29 -0600
                Re: srand(0) Paul <nospam@needed.invalid> - 2025-12-25 23:25 -0500
                Re: srand(0) BGB <cr88192@gmail.com> - 2025-12-25 23:41 -0600
                Re: srand(0) Lawrence D’Oliveiro <ldo@nz.invalid> - 2025-12-26 05:42 +0000
                Re: srand(0) Paul <nospam@needed.invalid> - 2025-12-26 01:52 -0500
                Re: srand(0) Lawrence D’Oliveiro <ldo@nz.invalid> - 2025-12-26 07:56 +0000
                Re: srand(0) BGB <cr88192@gmail.com> - 2025-12-26 04:48 -0600
      Re: srand(0) Michael S <already5chosen@yahoo.com> - 2025-12-24 10:51 +0200
        Re: srand(0) "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2025-12-24 00:59 -0800
        Re: srand(0) Michael Sanders <porkchop@invalid.foo> - 2025-12-24 15:28 +0000
          Re: srand(0) Michael S <already5chosen@yahoo.com> - 2025-12-24 17:44 +0200
            Re: srand(0) Michael Sanders <porkchop@invalid.foo> - 2025-12-24 16:17 +0000
              Re: srand(0) Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2025-12-24 17:53 +0100
                Re: srand(0) Michael Sanders <porkchop@invalid.foo> - 2025-12-24 17:27 +0000
                Re: srand(0) Michael Sanders <porkchop@invalid.foo> - 2025-12-24 17:33 +0000
                Re: srand(0) Michael S <already5chosen@yahoo.com> - 2025-12-24 20:16 +0200
                Re: srand(0) Michael Sanders <porkchop@invalid.foo> - 2025-12-25 02:01 +0000
                Re: srand(0) Lawrence D’Oliveiro <ldo@nz.invalid> - 2025-12-25 03:17 +0000
                Re: srand(0) Michael Sanders <porkchop@invalid.foo> - 2025-12-26 08:13 +0000
                Re: srand(0) Michael Sanders <porkchop@invalid.foo> - 2025-12-25 04:30 +0000
                Re: srand(0) Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2025-12-25 09:10 +0100
                Re: srand(0) Michael Sanders <porkchop@invalid.foo> - 2025-12-26 08:08 +0000
                Re: srand(0) Michael Sanders <porkchop@invalid.foo> - 2025-12-30 06:07 +0000
                Re: srand(0) scott@slp53.sl.home (Scott Lurndal) - 2025-12-30 18:42 +0000
                Re: srand(0) Michael Sanders <porkchop@invalid.foo> - 2025-12-31 02:01 +0000
                Re: srand(0) Lawrence D’Oliveiro <ldo@nz.invalid> - 2025-12-31 03:10 +0000
                Re: srand(0) Michael Sanders <porkchop@invalid.foo> - 2025-12-31 03:28 +0000
                Re: srand(0) Lawrence D’Oliveiro <ldo@nz.invalid> - 2025-12-31 09:37 +0000
                Re: srand(0) Michael Sanders <porkchop@invalid.foo> - 2026-01-01 07:32 +0000
                Re: srand(0) Lawrence D’Oliveiro <ldo@nz.invalid> - 2026-01-01 19:02 +0000
                Re: srand(0) Michael Sanders <porkchop@invalid.foo> - 2026-01-01 19:20 +0000
                Re: srand(0) Michael S <already5chosen@yahoo.com> - 2026-01-01 21:53 +0200
                Re: srand(0) Lawrence D’Oliveiro <ldo@nz.invalid> - 2026-01-01 23:50 +0000
                Re: srand(0) Michael S <already5chosen@yahoo.com> - 2026-01-02 14:32 +0200
                Re: srand(0) Michael S <already5chosen@yahoo.com> - 2026-01-02 16:18 +0200
                Re: srand(0) Lawrence D’Oliveiro <ldo@nz.invalid> - 2026-01-02 20:52 +0000
                Re: srand(0) Lawrence D’Oliveiro <ldo@nz.invalid> - 2026-01-02 20:46 +0000
                Re: srand(0) Mike Terry <news.dead.person.stones@darjeeling.plus.com> - 2026-01-03 04:08 +0000
                Re: srand(0) Lawrence D’Oliveiro <ldo@nz.invalid> - 2026-01-03 04:39 +0000
                Re: srand(0) Michael Sanders <porkchop@invalid.foo> - 2026-01-03 14:24 +0000
                Re: srand(0) Michael S <already5chosen@yahoo.com> - 2026-01-03 20:38 +0200
                Re: srand(0) Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2025-12-30 19:37 -0800
                Re: srand(0) scott@slp53.sl.home (Scott Lurndal) - 2025-12-31 17:24 +0000
                Re: srand(0) Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2025-12-31 15:17 -0800
                Re: srand(0) Paul <nospam@needed.invalid> - 2025-12-31 12:30 -0500
                Re: srand(0) bart <bc@freeuk.com> - 2025-12-31 18:42 +0000
                Re: srand(0) Paul <nospam@needed.invalid> - 2025-12-31 15:07 -0500
                Re: srand(0) Michael S <already5chosen@yahoo.com> - 2025-12-31 22:18 +0200
                Re: srand(0) Lawrence D’Oliveiro <ldo@nz.invalid> - 2025-12-31 20:55 +0000
                Re: srand(0) bart <bc@freeuk.com> - 2025-12-31 22:57 +0000
                Re: srand(0) Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2025-12-31 16:00 -0800
                Re: srand(0) Lawrence D’Oliveiro <ldo@nz.invalid> - 2026-01-01 01:03 +0000
                Re: srand(0) bart <bc@freeuk.com> - 2026-01-01 14:05 +0000
                Re: srand(0) Lawrence D’Oliveiro <ldo@nz.invalid> - 2026-01-01 19:03 +0000
                Re: srand(0) bart <bc@freeuk.com> - 2026-01-01 20:28 +0000
                Re: srand(0) Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2025-12-31 15:29 -0800
                Re: srand(0) highcrew <high.crew3868@fastmail.com> - 2026-01-01 00:31 +0100
                Re: srand(0) Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2025-12-31 16:05 -0800
                Re: srand(0) Michael S <already5chosen@yahoo.com> - 2025-12-31 15:29 +0200
                Re: srand(0) Lawrence D’Oliveiro <ldo@nz.invalid> - 2025-12-31 20:52 +0000
                Re: srand(0) Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2025-12-31 15:14 -0800
                Re: srand(0) Geoff <geoff@invalid.invalid> - 2026-01-05 20:00 -0800
                Re: srand(0) Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2025-12-31 15:03 -0800
                Re: srand(0) Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2025-12-30 19:35 -0800
                Re: srand(0) Michael Sanders <porkchop@invalid.foo> - 2025-12-31 04:51 +0000
                Re: srand(0) Michael S <already5chosen@yahoo.com> - 2025-12-31 15:15 +0200
                Re: srand(0) Lawrence D’Oliveiro <ldo@nz.invalid> - 2025-12-31 20:51 +0000
                Re: srand(0) Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2025-12-31 15:00 -0800
                Re: srand(0) Michael S <already5chosen@yahoo.com> - 2026-01-01 01:45 +0200
                Re: srand(0) Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2025-12-31 16:34 -0800
                Re: srand(0) Michael Sanders <porkchop@invalid.foo> - 2026-01-01 07:23 +0000
                Re: srand(0) Mike Terry <news.dead.person.stones@darjeeling.plus.com> - 2026-01-01 02:01 +0000
                Re: srand(0) Lawrence D’Oliveiro <ldo@nz.invalid> - 2026-01-01 02:29 +0000
                Re: srand(0) Lawrence D’Oliveiro <ldo@nz.invalid> - 2025-12-30 06:34 +0000
                Re: srand(0) Michael Sanders <porkchop@invalid.foo> - 2025-12-30 14:05 +0000
                Re: srand(0) Michael Sanders <porkchop@invalid.foo> - 2025-12-28 05:51 +0000
            Re: srand(0) scott@slp53.sl.home (Scott Lurndal) - 2025-12-24 17:08 +0000
    Re: srand(0) Tim Rentsch <tr.17687@z991.linuxsc.com> - 2026-01-07 07:39 -0800
      Re: srand(0) Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2026-01-07 13:54 -0800
        Re: srand(0) Michael Sanders <porkchop@invalid.foo> - 2026-01-08 15:34 +0000
          Re: srand(0) Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2026-01-08 14:44 -0800
            Re: srand(0) Michael Sanders <porkchop@invalid.foo> - 2026-01-09 06:06 +0000
              Re: srand(0) Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2026-01-08 22:46 -0800
                Re: srand(0) Michael Sanders <porkchop@invalid.foo> - 2026-01-09 22:38 +0000
                Re: srand(0) scott@slp53.sl.home (Scott Lurndal) - 2026-01-09 23:27 +0000
                Re: srand(0) Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2026-01-09 17:09 -0800
                Re: srand(0) Kaz Kylheku <046-301-5902@kylheku.com> - 2026-01-10 19:44 +0000
        Re: srand(0) Tim Rentsch <tr.17687@z991.linuxsc.com> - 2026-01-09 00:36 -0800
  Re: srand(0) Bonita Montero <Bonita.Montero@gmail.com> - 2025-12-23 11:04 +0100
  Re: srand(0) "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2025-12-23 21:44 -0800
    Re: srand(0) Michael Sanders <porkchop@invalid.foo> - 2025-12-24 15:41 +0000
      Re: srand(0) Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2025-12-24 18:04 +0100
        Re: srand(0) Michael Sanders <porkchop@invalid.foo> - 2025-12-25 05:41 +0000
  Re: srand(0) Michael Sanders <porkchop@invalid.foo> - 2026-01-08 02:57 +0000

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