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Re: Small challenge: sort names

From Tim Rentsch <tr.17687@z991.linuxsc.com>
Newsgroups comp.lang.c
Subject Re: Small challenge: sort names
Date 2026-04-25 13:31 -0700
Organization A noiseless patient Spider
Message-ID <86se8i3hoq.fsf@linuxsc.com> (permalink)
References (6 earlier) <bDBBR.139$Np7d.78@fx15.iad> <86h5pkww9a.fsf@linuxsc.com> <87cy0832zp.fsf@example.invalid> <86o6jo8f30.fsf@linuxsc.com> <878qar3h3x.fsf@example.invalid>

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Keith Thompson <Keith.S.Thompson+u@gmail.com> writes:

> Tim Rentsch <tr.17687@z991.linuxsc.com> writes:
>
>> Keith Thompson <Keith.S.Thompson+u@gmail.com> writes:
>>
>>> Tim Rentsch <tr.17687@z991.linuxsc.com> writes:
>>> [...]
>>>
>>>> The semantics of !ptr has been codified to mean 1 for null pointers
>>>> since the original C standard.  Heck, even during the 1970s when C
>>>> allowed assigning integers directly to pointers, K&R said that
>>>> assigning 0 to a pointer produces a pointer guaranteed to be
>>>> different than a pointer to any object.  Any C implementation where
>>>> !ptr does the wrong thing should be avoided like the plague.
>>>
>>> Any C implementation where !ptr does the wrong thing almost certainly
>>> does not exist.  It's difficult to imagine that a C compiler with
>>> such a fundamental bug would ever go out the door.
>>
>> My usual preference is to draw conclusions based on evidence rather
>> imagination or supposition.
>
> Good for you.
>
>>> It's barely possible that compiler that uses a representation other
>>> than all-bits-zero for null pointers might have such a bug, but
>>> (a) anyone creating such an implementation will almost certainly
>>> be extremely careful to get such things right, and (b) I'm not sure
>>> that any such compilers even exist, except perhaps for old systems
>>> that would be considered exotic today.
>>
>> Here again this sounds like just supposition.  How much experience
>> do you have, and how extensive, using non-mainstream C compilers?
>> For myself I can't say I much at all, but I have seen one where
>> believe it or not assert() was implemented wrongly.  assert()!  I
>> certainly wouldn't have guessed that before actually seeing it.
>
> Quick summary:  You wrote that "Any C implementation where !ptr does
> the wrong thing should be avoided like the plague."  My response
> was, to summarize briefly, that such implementations are unlikely
> to exist and not worth worrying about.

You said "Any C implementation where !ptr does the wrong thing
almost certainly does not exist."

> Do you disagree, or are you just criticizing the way I said it?

I was simply drawing attention to the circumstance of your having
made a statement of fact without offering any facts to support it.

> I believe I was clear about the basis for my statement.  No, I don't
> have a lot of experience with non-mainstream C compilers.  I'm not
> going to perform a survey of all historical C implementations.
>
> Do you have anything useful to say about my point, as opposed to
> how I expressed it?

As far as I can tell your point is that you don't mind offering
unsupported allegations as facts.  In my opinion it is useful
to have that attitude pointed out.

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Thread

Re: Small challenge: sort names Tim Rentsch <tr.17687@z991.linuxsc.com> - 2026-04-08 22:14 -0700
  Re: Small challenge: sort names Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2026-04-09 02:19 -0700
    Re: Small challenge: sort names scott@slp53.sl.home (Scott Lurndal) - 2026-04-09 15:06 +0000
      Re: Small challenge: sort names Tim Rentsch <tr.17687@z991.linuxsc.com> - 2026-04-12 06:35 -0700
        Re: Small challenge: sort names scott@slp53.sl.home (Scott Lurndal) - 2026-04-12 14:51 +0000
          Re: Small challenge: sort names Tim Rentsch <tr.17687@z991.linuxsc.com> - 2026-04-13 06:31 -0700
    Re: Small challenge: sort names Tim Rentsch <tr.17687@z991.linuxsc.com> - 2026-04-12 06:48 -0700
      Re: Small challenge: sort names Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2026-04-12 16:15 -0700
        Re: Small challenge: sort names Tim Rentsch <tr.17687@z991.linuxsc.com> - 2026-04-25 13:31 -0700
          Re: Small challenge: sort names Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2026-04-25 15:12 -0700
            Re: Small challenge: sort names Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2026-04-26 04:13 +0200
              Re: Small challenge: sort names Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2026-04-25 19:50 -0700
                Re: Small challenge: sort names Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2026-04-26 05:28 +0200
                Re: Small challenge: sort names David Brown <david.brown@hesbynett.no> - 2026-04-26 12:08 +0200
                Re: Small challenge: sort names Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2026-04-26 18:16 +0200
                Re: Small challenge: sort names David Brown <david.brown@hesbynett.no> - 2026-04-26 19:37 +0200
                Re: Small challenge: sort names Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2026-04-27 02:17 +0200
                Re: Small challenge: sort names David Brown <david.brown@hesbynett.no> - 2026-04-27 09:19 +0200
                Re: Small challenge: sort names scott@slp53.sl.home (Scott Lurndal) - 2026-04-26 17:47 +0000
                Re: Small challenge: sort names Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2026-04-27 02:33 +0200
                Re: Small challenge: sort names David Brown <david.brown@hesbynett.no> - 2026-04-27 09:34 +0200
                Re: Small challenge: sort names Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2026-04-27 12:35 +0200
                Re: Small challenge: sort names Bart <bc@freeuk.com> - 2026-04-27 13:28 +0100
                Re: Small challenge: sort names Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2026-04-27 17:02 +0200
                Re: Small challenge: sort names Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2026-04-27 17:36 +0200
                Re: Small challenge: sort names scott@slp53.sl.home (Scott Lurndal) - 2026-04-27 16:18 +0000
                Re: Small challenge: sort names Michael S <already5chosen@yahoo.com> - 2026-04-27 11:42 +0300
                Re: Small challenge: sort names scott@slp53.sl.home (Scott Lurndal) - 2026-04-27 16:27 +0000
                Assembler verb choice (Was: Small challenge: sort names) gazelle@shell.xmission.com (Kenny McCormack) - 2026-04-28 12:59 +0000
                Re: Assembler verb choice (Was: Small challenge: sort names) Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2026-04-28 16:26 +0200
                Re: Small challenge: sort names "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2026-04-27 12:45 -0700
                Re: Small challenge: sort names "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2026-04-27 12:42 -0700
                Re: Small challenge: sort names "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2026-04-27 12:43 -0700
                Re: Small challenge: sort names Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2026-04-27 12:59 -0700
                Re: Small challenge: sort names "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2026-04-27 13:26 -0700
                Re: Small challenge: sort names cross@spitfire.i.gajendra.net (Dan Cross) - 2026-04-27 20:43 +0000
                Re: Small challenge: sort names "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2026-04-27 17:30 -0700
                Re: Small challenge: sort names Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2026-04-27 19:15 -0700
                Re: Small challenge: sort names gazelle@shell.xmission.com (Kenny McCormack) - 2026-04-28 12:01 +0000
                Re: Small challenge: sort names David Brown <david.brown@hesbynett.no> - 2026-04-28 08:35 +0200
                Re: Small challenge: sort names cross@spitfire.i.gajendra.net (Dan Cross) - 2026-04-28 13:27 +0000
                Re: Small challenge: sort names David Brown <david.brown@hesbynett.no> - 2026-04-28 15:59 +0200
                Re: Small challenge: sort names Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2026-04-28 16:49 +0200
                Re: Small challenge: sort names David Brown <david.brown@hesbynett.no> - 2026-04-28 17:25 +0200
                Re: Small challenge: sort names Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2026-04-28 23:46 +0200
                Re: Small challenge: sort names cross@spitfire.i.gajendra.net (Dan Cross) - 2026-04-28 18:12 +0000
                Re: Small challenge: sort names David Brown <david.brown@hesbynett.no> - 2026-04-28 20:28 +0200
            Re: Small challenge: sort names vallor <vallor@vallor.earth> - 2026-04-28 13:45 +0000

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