Re: MISRA C

From	bart <bc@freeuk.com>
Newsgroups	comp.lang.c
Subject	Re: MISRA C
Date	2026-09-28 13:07 +0100
Organization	A noiseless patient Spider
Message-ID	<119dla5$2af5o$1@dont-email.me> (permalink)
References	(12 earlier) <1195qr8$2aem2$1@dont-email.me> <1195u2r$16ah$1@news.muc.de> <119612d$2aem2$2@dont-email.me> <11962u0$16ah$2@news.muc.de> <119dhqt$1uucd$1@dont-email.me>

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On 28/09/2026 12:08, Janis Papanagnou wrote:
> On 2026-09-25 17:10, Alan Mackenzie wrote:
>> Janis Papanagnou <janis_papanagnou+ng@hotmail.com> wrote:
>>> On 2026-09-25 15:48, Alan Mackenzie wrote:
>>>> Janis Papanagnou <janis_papanagnou+ng@hotmail.com> wrote:
>>
>> [ .... ]
>>
>>>>> WRT Dude's statement it should be mentioned that a recursive algorithm
>>>>> can be transformed to an iterative one, so if iterative algorithms
>>>>> would have the property to be _decidable_ to finish - actually, they
>>>>> are not - we could also say the same for a recursive one.
>>
>>>> Recursion can often be programmed iteratively in practice.  In theory,
>>>> there are recursively defined functions which grow too quickly with
>>>> increasing argument to be definable (or programmable) without 
>>>> recursion.
>>
>>> Have you functions like fib() in mind? - Despite they are cascaded
>>> recursion you can create iterative ones. - But it's simpler; just
>>> recognize that a recursion is using an implicit stack, so you can
>>> write it in iterative form with an explicit stack. Even an extreme
>>> function like Ackermann (which is more demanding) is not exempt to
>>> that principle. - Or do you disagree? (Then please explain - best
>>> with an example you may have in mind.)
>>
>> Yes, it was the Ackermann function I had in mind (though I'd forgotten
>> its name).  It's a function of two natural number arguments.  Simply
>> making both arguments the same gives a function of one argument.
>>
>> [...]
>>
>> This function can't be calculated iteratively, since there's no
>> non-recursive way of calculating how big the requisite static arrays
>> would have to be.  Or something like that.
> 
> Franky, I'm too lazy now to derive the iterative form myself. But
> if you're not convinced by the principle considerations it's fairly
> easy to ask an AI to create some C-code, verify that it has no
> recursive calls, and check its results. - The code that the AI had
> provided to me seems to work well.[*]
Actually any recursive code in C can be implemented without recursion. 
You don't have to change the source code. Example:

   c:\cx>cc -r ack
   Compiling ack.c to ack.(run)
   A= 8189

   c:\cx>cc -i ack
   Compiling ack.c to ack.(int)
   A= 8189

The first invocation runs native code that uses actual recursive calls 
with a hardware stack.

The second invocation interprets it. It uses a software stack, and an 
iterative loop to execute the bytecode instructions.

The difference from your machine-generated Ackermann is that that was 
specific to the task, but my approach can run C programs in general 
without a stack.

(It also uses a hardware stack for some features of the interpreter, but 
your version uses one too for the function calls.)

Thread

MISRA C (was: buckle-up ....) Alan Mackenzie <acm@muc.de> - 2026-09-25 10:01 +0000
  Re: MISRA C Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2026-09-25 14:52 +0200
    Re: MISRA C Alan Mackenzie <acm@muc.de> - 2026-09-25 13:48 +0000
      Re: MISRA C Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2026-09-25 16:39 +0200
        Re: MISRA C Alan Mackenzie <acm@muc.de> - 2026-09-25 15:10 +0000
          Re: MISRA C bart <bc@freeuk.com> - 2026-09-25 16:57 +0100
          Re: MISRA C Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2026-09-25 11:42 -0700
            Re: MISRA C Alan Mackenzie <acm@muc.de> - 2026-09-25 20:21 +0000
              Re: MISRA C Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2026-09-25 14:05 -0700
                Re: MISRA C David Brown <david.brown@hesbynett.no> - 2026-09-26 08:43 +0200
                Re: MISRA C Alan Mackenzie <acm@muc.de> - 2026-09-26 17:55 +0000
                Re: MISRA C Ben Bacarisse <ben@bsb.me.uk> - 2026-10-03 23:55 +0100
                Re: MISRA C David Brown <david.brown@hesbynett.no> - 2026-10-04 16:10 +0200
                Re: MISRA C Ben Bacarisse <ben@bsb.me.uk> - 2026-10-05 01:22 +0100
                Re: MISRA C David Brown <david.brown@hesbynett.no> - 2026-10-05 07:59 +0200
                Re: MISRA C Tim Rentsch <tr.17687@z991.linuxsc.com> - 2026-10-05 01:23 -0700
                Re: MISRA C Tim Rentsch <tr.17687@z991.linuxsc.com> - 2026-10-05 01:24 -0700
                Re: MISRA C antispam@fricas.org (Waldek Hebisch) - 2026-10-05 09:02 +0000
                Re: MISRA C Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2026-10-05 12:07 +0200
                Re: MISRA C Ben Bacarisse <ben@bsb.me.uk> - 2026-10-05 15:29 +0100
                Re: MISRA C antispam@fricas.org (Waldek Hebisch) - 2026-10-05 20:29 +0000
                Re: MISRA C Tim Rentsch <tr.17687@z991.linuxsc.com> - 2026-10-06 22:13 -0700
                Re: MISRA C Tim Rentsch <tr.17687@z991.linuxsc.com> - 2026-10-06 22:14 -0700
          Re: MISRA C Tim Rentsch <tr.17687@z991.linuxsc.com> - 2026-09-27 10:52 -0700
          Re: MISRA C Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2026-09-28 13:08 +0200
            Re: MISRA C bart <bc@freeuk.com> - 2026-09-28 13:07 +0100
            Re: MISRA C David Brown <david.brown@hesbynett.no> - 2026-09-28 14:08 +0200
              Re: MISRA C Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2026-09-28 14:28 +0200
            Re: MISRA C Alan Mackenzie <acm@muc.de> - 2026-09-28 12:17 +0000
              Re: MISRA C Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2026-09-28 14:40 +0200
          Re: MISRA C "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2026-09-30 10:21 -0700
            Re: MISRA C Alan Mackenzie <acm@muc.de> - 2026-09-30 19:57 +0000
              Re: MISRA C "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2026-09-30 13:09 -0700
                Re: MISRA C David Brown <david.brown@hesbynett.no> - 2026-10-01 08:47 +0200
                Re: MISRA C "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2026-10-01 15:18 -0700
      Re: MISRA C Johann 'Myrkraverk' Oskarsson <johann@myrkraverk.invalid> - 2026-09-27 04:58 +0800
  Re: MISRA C David Brown <david.brown@hesbynett.no> - 2026-09-25 17:02 +0200
  Re: MISRA C "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2026-09-26 15:37 -0700

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