Re: encapsulating directory operations

From	Tim Rentsch <tr.17687@z991.linuxsc.com>
Newsgroups	comp.lang.c
Subject	Re: encapsulating directory operations
Date	2025-07-01 10:09 -0700
Organization	A noiseless patient Spider
Message-ID	<86bjq3q1mw.fsf@linuxsc.com> (permalink)
References	(16 earlier) <10196gn$3pd33$1@dont-email.me> <10199t2$3q3mn$1@dont-email.me> <1019kgf$3s5co$1@dont-email.me> <101bt9c$dckn$2@dont-email.me> <101c2p8$eeca$2@dont-email.me>

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Richard Heathfield <rjh@cpax.org.uk> writes:

> On 30/05/2025 10:20, David Brown wrote:
>
>> On 29/05/2025 14:38, Richard Heathfield wrote:
>>
>>> This really is a very simple point, but perhaps a simple analogy
>>> will help to clarify it.  You don't throw out your 3/4" just
>>> because you've bought a 19mm.  There is room for both in the
>>> toolbox, and why write 3/4" on your new spanner?  It /isn't/ a
>>> 3/4" spanner even though it's very like it, so why pretend
>>> otherwise?
>>
>> Your analogy does not cover C99 vs C90.
>
> It does if we can construct a program that is legal C90 but not
> legal C99, which is easy enough, or (slightly harder but still not
> that hard) a program that is legal in both dialects but which
> gives different output under C99 than it does for C90.
>
> $ cat c9099.c; \
>     gcc -W -Wall -ansi -pedantic -o c90 c9099.c; \
>     gcc -o c99 c9099.c; \
>    ./c90; \
>    ./c99
> #include <stdio.h>
>
> int main(void)
> {
>   int a = 42;
>
>   int b = a //* comment */ 6;
>   ;
>   printf("Soln = %d\n", b);
>
>   return 0;
> }
> Soln = 7
> Soln = 42

It's a straightfoward exercise to write a program that discovers
whether a given .c file has this potential ambiguity.  Of course,
essentially no actual source code will, but the point is the
problem is easy to detect, and also correct.

This observation suggests a related question.  Is there a source
of potential ambiguity between C90 and C99 that is not so easy to
detect and correct?  I can think of one, but it falls into the
realm of depending on implementation-specific behavior, so could
just as easily be seen as a portability issue rather than a
language version issue.

> Obviously it's a contrived example, but then examples pointing out
> the consequences of language differences invariably are.

Some are.  Some are not.  In the case of C90 and C99, probably
all such cases are contrived, but certainly for other language
pairs there are cases that might arise unintentionally, even for
similar languages (notably C and C++).

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Re: encapsulating directory operations Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2025-05-20 14:41 -0700
  Re: encapsulating directory operations "Paul Edwards" <mutazilah@gmail.com> - 2025-05-21 08:38 +1000
    Re: encapsulating directory operations "Paul Edwards" <mutazilah@gmail.com> - 2025-05-21 09:09 +1000
      Re: encapsulating directory operations Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2025-05-20 16:22 -0700
      Re: encapsulating directory operations Kaz Kylheku <643-408-1753@kylheku.com> - 2025-05-21 00:18 +0000
        Re: encapsulating directory operations "Paul Edwards" <mutazilah@gmail.com> - 2025-05-21 10:31 +1000
      Re: encapsulating directory operations Lawrence D'Oliveiro <ldo@nz.invalid> - 2025-05-21 01:02 +0000
    Re: encapsulating directory operations Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2025-05-20 16:18 -0700
      Re: encapsulating directory operations "Paul Edwards" <mutazilah@gmail.com> - 2025-05-21 09:57 +1000
        Re: encapsulating directory operations Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2025-05-20 22:41 -0700
          Re: encapsulating directory operations "Paul Edwards" <mutazilah@gmail.com> - 2025-05-21 20:41 +1000
            Re: encapsulating directory operations Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2025-05-21 11:06 -0700
              Re: encapsulating directory operations Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2025-05-21 11:22 -0700
              Re: encapsulating directory operations scott@slp53.sl.home (Scott Lurndal) - 2025-05-21 20:58 +0000
              Re: encapsulating directory operations "Paul Edwards" <mutazilah@gmail.com> - 2025-05-23 07:10 +1000
                Re: encapsulating directory operations Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2025-05-22 15:32 -0700
                Re: encapsulating directory operations "Paul Edwards" <mutazilah@gmail.com> - 2025-05-23 09:16 +1000
                Re: encapsulating directory operations Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2025-05-22 18:38 -0700
                Re: encapsulating directory operations "Paul Edwards" <mutazilah@gmail.com> - 2025-05-26 08:12 +1000
                Re: encapsulating directory operations Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2025-05-25 15:34 -0700
                Re: encapsulating directory operations "Paul Edwards" <mutazilah@gmail.com> - 2025-05-26 09:01 +1000
                Re: encapsulating directory operations gazelle@shell.xmission.com (Kenny McCormack) - 2025-05-25 23:25 +0000
                Re: encapsulating directory operations Kaz Kylheku <643-408-1753@kylheku.com> - 2025-05-23 02:28 +0000
                Re: encapsulating directory operations Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2025-05-22 21:27 -0700
                Re: encapsulating directory operations Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2025-05-23 07:08 +0200
                Re: encapsulating directory operations Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2025-05-22 22:20 -0700
                Re: encapsulating directory operations Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2025-05-23 07:43 +0200
                Re: encapsulating directory operations "Paul Edwards" <mutazilah@gmail.com> - 2025-05-26 07:54 +1000
                Re: encapsulating directory operations Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2025-05-25 15:29 -0700
                Re: encapsulating directory operations "Paul Edwards" <mutazilah@gmail.com> - 2025-05-26 08:40 +1000
                Re: encapsulating directory operations Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2025-05-26 03:29 +0200
                Re: encapsulating directory operations "Paul Edwards" <mutazilah@gmail.com> - 2025-05-26 11:46 +1000
                Re: encapsulating directory operations James Kuyper <jameskuyper@alumni.caltech.edu> - 2025-05-26 09:43 -0400
                Re: encapsulating directory operations Kaz Kylheku <643-408-1753@kylheku.com> - 2025-05-26 17:16 +0000
                Re: encapsulating directory operations vallor <vallor@cultnix.org> - 2025-05-26 04:05 +0000
                Re: encapsulating directory operations "Paul Edwards" <mutazilah@gmail.com> - 2025-05-26 08:31 +1000
                Re: encapsulating directory operations Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2025-05-26 03:37 +0200
                Re: encapsulating directory operations Richard Harnden <richard.harnden@gmail.invalid> - 2025-05-23 16:09 +0100
                Re: encapsulating directory operations Richard Heathfield <rjh@cpax.org.uk> - 2025-05-23 17:50 +0100
                Re: encapsulating directory operations scott@slp53.sl.home (Scott Lurndal) - 2025-05-23 16:57 +0000
                Re: encapsulating directory operations Richard Heathfield <rjh@cpax.org.uk> - 2025-05-23 18:00 +0100
                Re: encapsulating directory operations Kaz Kylheku <643-408-1753@kylheku.com> - 2025-05-23 17:22 +0000
                Re: encapsulating directory operations Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2025-05-23 11:10 -0700
                Re: encapsulating directory operations Kaz Kylheku <643-408-1753@kylheku.com> - 2025-05-23 20:27 +0000
                Re: encapsulating directory operations Richard Heathfield <rjh@cpax.org.uk> - 2025-05-23 21:35 +0100
                Re: encapsulating directory operations Kaz Kylheku <643-408-1753@kylheku.com> - 2025-05-23 21:10 +0000
                Re: encapsulating directory operations Richard Heathfield <rjh@cpax.org.uk> - 2025-05-23 23:13 +0100
                Re: encapsulating directory operations Tim Rentsch <tr.17687@z991.linuxsc.com> - 2025-05-23 22:22 -0700
                Re: encapsulating directory operations Richard Heathfield <rjh@cpax.org.uk> - 2025-05-24 06:46 +0100
                Re: encapsulating directory operations Lawrence D'Oliveiro <ldo@nz.invalid> - 2025-05-29 07:27 +0000
                Re: encapsulating directory operations Richard Heathfield <rjh@cpax.org.uk> - 2025-05-29 09:39 +0100
                Re: encapsulating directory operations Lawrence D'Oliveiro <ldo@nz.invalid> - 2025-05-29 09:37 +0000
                Re: encapsulating directory operations James Kuyper <jameskuyper@alumni.caltech.edu> - 2025-05-29 06:11 -0400
                Re: encapsulating directory operations Richard Heathfield <rjh@cpax.org.uk> - 2025-05-29 13:41 +0100
                Re: encapsulating directory operations scott@slp53.sl.home (Scott Lurndal) - 2025-05-29 15:08 +0000
                Re: encapsulating directory operations Richard Heathfield <rjh@cpax.org.uk> - 2025-05-29 17:36 +0100
                Re: encapsulating directory operations Kaz Kylheku <643-408-1753@kylheku.com> - 2025-05-29 17:18 +0000
                Re: encapsulating directory operations Richard Heathfield <rjh@cpax.org.uk> - 2025-05-29 18:51 +0100
                Re: encapsulating directory operations "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2025-05-29 14:31 -0700
                Re: encapsulating directory operations "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2025-05-29 14:29 -0700
                Re: encapsulating directory operations Richard Heathfield <rjh@cpax.org.uk> - 2025-05-29 13:38 +0100
                Re: encapsulating directory operations James Kuyper <jameskuyper@alumni.caltech.edu> - 2025-05-29 12:55 -0400
                Re: encapsulating directory operations Richard Heathfield <rjh@cpax.org.uk> - 2025-05-29 18:48 +0100
                Re: encapsulating directory operations Lawrence D'Oliveiro <ldo@nz.invalid> - 2025-05-30 03:10 +0000
                Re: encapsulating directory operations David Brown <david.brown@hesbynett.no> - 2025-05-30 11:20 +0200
                Re: encapsulating directory operations Richard Heathfield <rjh@cpax.org.uk> - 2025-05-30 11:54 +0100
                Re: encapsulating directory operations David Brown <david.brown@hesbynett.no> - 2025-05-30 16:02 +0200
                Re: encapsulating directory operations Richard Heathfield <rjh@cpax.org.uk> - 2025-05-30 16:26 +0100
                Re: encapsulating directory operations David Brown <david.brown@hesbynett.no> - 2025-05-30 17:42 +0200
                Re: encapsulating directory operations Richard Heathfield <rjh@cpax.org.uk> - 2025-05-30 17:39 +0100
                Re: encapsulating directory operations Tim Rentsch <tr.17687@z991.linuxsc.com> - 2025-07-01 10:09 -0700
                Re: encapsulating directory operations Kaz Kylheku <643-408-1753@kylheku.com> - 2025-05-30 18:04 +0000
                Re: encapsulating directory operations David Brown <david.brown@hesbynett.no> - 2025-05-29 21:24 +0200
                Re: encapsulating directory operations Michael S <already5chosen@yahoo.com> - 2025-05-29 23:24 +0300
                Re: encapsulating directory operations Richard Heathfield <rjh@cpax.org.uk> - 2025-05-29 21:27 +0100
                Re: encapsulating directory operations Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2025-05-29 13:45 -0700
                Re: encapsulating directory operations Richard Heathfield <rjh@cpax.org.uk> - 2025-05-29 22:09 +0100
                Re: encapsulating directory operations scott@slp53.sl.home (Scott Lurndal) - 2025-05-29 21:19 +0000
                Re: encapsulating directory operations Richard Heathfield <rjh@cpax.org.uk> - 2025-05-29 22:40 +0100
                Re: encapsulating directory operations "Paul Edwards" <mutazilah@gmail.com> - 2025-05-30 18:18 +1000
                Re: encapsulating directory operations Lawrence D'Oliveiro <ldo@nz.invalid> - 2025-05-30 22:10 +0000
                Re: encapsulating directory operations "Paul Edwards" <mutazilah@gmail.com> - 2025-06-04 19:23 +1000
                Re: encapsulating directory operations scott@slp53.sl.home (Scott Lurndal) - 2025-06-04 13:05 +0000
                Re: encapsulating directory operations "Paul Edwards" <mutazilah@gmail.com> - 2025-06-05 00:00 +1000
                Re: encapsulating directory operations David Brown <david.brown@hesbynett.no> - 2025-06-04 17:30 +0200
                Re: encapsulating directory operations Josef Möllers <josef@invalid.invalid> - 2025-06-04 20:48 +0200
                Re: encapsulating directory operations scott@slp53.sl.home (Scott Lurndal) - 2025-06-04 21:09 +0000
                Re: encapsulating directory operations David Brown <david.brown@hesbynett.no> - 2025-06-05 08:18 +0200
                Re: encapsulating directory operations "Paul Edwards" <mutazilah@gmail.com> - 2025-06-05 04:58 +1000
                Re: encapsulating directory operations Kaz Kylheku <643-408-1753@kylheku.com> - 2025-06-04 19:19 +0000
                Re: encapsulating directory operations "Paul Edwards" <mutazilah@gmail.com> - 2025-06-05 05:24 +1000
                Re: encapsulating directory operations Kaz Kylheku <643-408-1753@kylheku.com> - 2025-06-04 21:30 +0000
                Re: encapsulating directory operations scott@slp53.sl.home (Scott Lurndal) - 2025-06-04 22:38 +0000
                Re: encapsulating directory operations "Paul Edwards" <mutazilah@gmail.com> - 2025-06-05 19:31 +1000
                Re: encapsulating directory operations David Brown <david.brown@hesbynett.no> - 2025-06-05 08:32 +0200
                Re: encapsulating directory operations "Paul Edwards" <mutazilah@gmail.com> - 2025-06-05 19:28 +1000
                Re: encapsulating directory operations "Paul Edwards" <mutazilah@gmail.com> - 2025-06-05 20:25 +1000
                Re: encapsulating directory operations antispam@fricas.org (Waldek Hebisch) - 2025-06-06 03:26 +0000
                Re: encapsulating directory operations Lawrence D'Oliveiro <ldo@nz.invalid> - 2025-06-04 23:22 +0000
                Re: encapsulating directory operations scott@slp53.sl.home (Scott Lurndal) - 2025-06-04 23:48 +0000
                Re: encapsulating directory operations Tim Rentsch <tr.17687@z991.linuxsc.com> - 2025-06-10 07:18 -0700
                Re: encapsulating directory operations Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2025-05-29 14:50 -0700
                Re: encapsulating directory operations Richard Heathfield <rjh@cpax.org.uk> - 2025-05-30 00:05 +0100
                Re: encapsulating directory operations David Brown <david.brown@hesbynett.no> - 2025-05-30 17:37 +0200
                Re: encapsulating directory operations Richard Harnden <richard.nospam@gmail.invalid> - 2025-05-30 17:25 +0100
                Re: encapsulating directory operations Richard Heathfield <rjh@cpax.org.uk> - 2025-05-30 17:39 +0100
                Re: encapsulating directory operations Richard Heathfield <rjh@cpax.org.uk> - 2025-05-30 17:32 +0100
                Re: encapsulating directory operations antispam@fricas.org (Waldek Hebisch) - 2025-05-30 02:46 +0000
                Re: encapsulating directory operations Kaz Kylheku <643-408-1753@kylheku.com> - 2025-05-30 03:42 +0000
                Re: encapsulating directory operations Lawrence D'Oliveiro <ldo@nz.invalid> - 2025-05-30 07:34 +0000
                Re: encapsulating directory operations scott@slp53.sl.home (Scott Lurndal) - 2025-05-23 21:10 +0000
                Re: encapsulating directory operations Kaz Kylheku <643-408-1753@kylheku.com> - 2025-05-23 21:31 +0000
                Re: encapsulating directory operations Tim Rentsch <tr.17687@z991.linuxsc.com> - 2025-05-23 22:05 -0700
                Re: encapsulating directory operations Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2025-05-24 01:27 -0700
                Re: encapsulating directory operations Tim Rentsch <tr.17687@z991.linuxsc.com> - 2025-06-10 08:52 -0700
                Re: encapsulating directory operations Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2025-06-10 13:35 -0700
                Re: encapsulating directory operations Kaz Kylheku <643-408-1753@kylheku.com> - 2025-06-10 21:34 +0000
                Re: encapsulating directory operations Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2025-06-10 15:09 -0700
                Re: encapsulating directory operations Kaz Kylheku <643-408-1753@kylheku.com> - 2025-06-11 01:16 +0000
                Re: encapsulating directory operations Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2025-06-10 19:11 -0700
                Re: encapsulating directory operations Kaz Kylheku <643-408-1753@kylheku.com> - 2025-06-11 15:23 +0000
                Re: encapsulating directory operations "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2025-06-11 11:57 -0700
                Re: encapsulating directory operations Kaz Kylheku <643-408-1753@kylheku.com> - 2025-06-11 15:32 +0000
                Re: encapsulating directory operations "Paul Edwards" <mutazilah@gmail.com> - 2025-05-23 08:44 +1000
              Re: encapsulating directory operations "Paul Edwards" <mutazilah@gmail.com> - 2025-05-23 08:06 +1000
                Re: encapsulating directory operations Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2025-05-22 18:24 -0700
                Re: encapsulating directory operations Kaz Kylheku <643-408-1753@kylheku.com> - 2025-05-23 02:19 +0000
            Re: encapsulating directory operations Kaz Kylheku <643-408-1753@kylheku.com> - 2025-05-21 19:31 +0000
              Re: encapsulating directory operations "Paul Edwards" <mutazilah@gmail.com> - 2025-05-23 07:45 +1000
          Re: encapsulating directory operations scott@slp53.sl.home (Scott Lurndal) - 2025-05-21 13:59 +0000
            Re: encapsulating directory operations "Paul Edwards" <mutazilah@gmail.com> - 2025-05-23 07:52 +1000
              Re: encapsulating directory operations Lawrence D'Oliveiro <ldo@nz.invalid> - 2025-05-23 01:18 +0000
                Re: encapsulating directory operations "Paul Edwards" <mutazilah@gmail.com> - 2025-05-26 09:48 +1000
                Re: encapsulating directory operations Lawrence D'Oliveiro <ldo@nz.invalid> - 2025-05-26 00:15 +0000
                Re: encapsulating directory operations "Paul Edwards" <mutazilah@gmail.com> - 2025-05-26 11:50 +1000
                Re: encapsulating directory operations Lawrence D'Oliveiro <ldo@nz.invalid> - 2025-05-29 07:26 +0000
                Re: encapsulating directory operations "Paul Edwards" <mutazilah@gmail.com> - 2025-05-30 18:47 +1000
      Re: encapsulating directory operations Kaz Kylheku <643-408-1753@kylheku.com> - 2025-05-21 02:21 +0000
        Re: encapsulating directory operations Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2025-05-20 22:49 -0700
          Re: encapsulating directory operations "Paul Edwards" <mutazilah@gmail.com> - 2025-05-21 20:44 +1000
            Re: encapsulating directory operations Richard Heathfield <rjh@cpax.org.uk> - 2025-05-21 12:06 +0100
            Re: encapsulating directory operations Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2025-05-21 11:15 -0700
              Re: encapsulating directory operations scott@slp53.sl.home (Scott Lurndal) - 2025-05-21 21:02 +0000
          Re: encapsulating directory operations Kaz Kylheku <643-408-1753@kylheku.com> - 2025-05-21 19:49 +0000
        Re: encapsulating directory operations "Paul Edwards" <mutazilah@gmail.com> - 2025-05-21 19:38 +1000
    Re: encapsulating directory operations James Kuyper <jameskuyper@alumni.caltech.edu> - 2025-05-20 22:26 -0400
      Re: encapsulating directory operations Lawrence D'Oliveiro <ldo@nz.invalid> - 2025-05-21 03:32 +0000
        Re: encapsulating directory operations "Paul Edwards" <mutazilah@gmail.com> - 2025-05-21 19:50 +1000
          Re: encapsulating directory operations Lawrence D'Oliveiro <ldo@nz.invalid> - 2025-05-22 00:03 +0000
          Re: encapsulating directory operations Jakob Bohm <egenagwemdimtapsar@jbohm.dk> - 2025-05-22 02:20 +0200
            Re: encapsulating directory operations Lawrence D'Oliveiro <ldo@nz.invalid> - 2025-05-22 02:53 +0000
              Re: encapsulating directory operations Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2025-05-21 22:14 -0700
                Re: encapsulating directory operations Jakob Bohm <egenagwemdimtapsar@jbohm.dk> - 2025-08-17 22:34 +0200
    Re: encapsulating directory operations antispam@fricas.org (Waldek Hebisch) - 2025-05-21 21:19 +0000
      Re: encapsulating directory operations Lawrence D'Oliveiro <ldo@nz.invalid> - 2025-05-23 01:17 +0000

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