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Re: Loops (was Re: do { quit; } else { })

From Tim Rentsch <tr.17687@z991.linuxsc.com>
Newsgroups comp.lang.c
Subject Re: Loops (was Re: do { quit; } else { })
Date 2025-05-13 15:10 -0700
Organization A noiseless patient Spider
Message-ID <86msbgw49b.fsf@linuxsc.com> (permalink)
References (16 earlier) <vvpsji$4jht$1@dont-email.me> <vvr5mg$l85c$1@dont-email.me> <vvt2tg$14otk$2@dont-email.me> <1000cs3$2234m$1@dont-email.me> <87sel8nqid.fsf@nosuchdomain.example.com>

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

> Janis Papanagnou <janis_papanagnou+ng@hotmail.com> writes:
>
>> On 12.05.2025 17:08, David Brown wrote:
>>
>>> On 11/05/2025 23:43, James Kuyper wrote:
>>
>> [...]
>>
>>>> More precisely, it makes it undefined behavior for values to point to an
>>>> array of less than 10 doubles.
>>>
>>> The wording of the C standard (C11, as that's what I have open at the
>>> moment) is :
>>>
>>> """
>>> If the keyword static also appears within the [ and ] of the array type
>>> derivation, then for each call to the function, the value of the
>>> corresponding actual argument shall provide access to the first element
>>> of an array with at least as many elements as specified by the size
>>> expression.
>>> """
>>
>> Oh! - This is somewhat surprising to me. - When I first read about
>> the "arr[static N]" I assumed that it would be possible to pass any
>> sub-array, say "&arr[8]" (or "arr+8") as long as it's large enough
>> to still have N elements from the starting point, but the quote says
>> explicitly "access to the _first_ element of an array" (which I'd
>> interpret as "&arr[0]" (or "arr"). - Unless I misinterpreted that;
>> what would be the reason for that?
>
> My personal interpretation is that this:
>
> void func(int arr[static 5]) {
> }
>
> int main(void) {
>     int arr[10];
>     func(arr+5);    // OK
>     // func(arr+6); // UB
> }
>
> is valid, because, for example, the last 5 elements of a 10-element
> array object can be treated as a 5-element array object.  gcc seems
> to agree, based on the fact that it warns about func(arr+6) but
> not about func(arr+5).
>
> This is a fundamental part of my mental model of C, but in a few
> minutes of searching I wasn't able to find explicit wording in the
> standard that supports it.

In N1570, 6.7.6.3 p7.

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Re: Loops (was Re: do { quit; } else { }) Tim Rentsch <tr.17687@z991.linuxsc.com> - 2025-05-04 07:31 -0700
  Re: Loops (was Re: do { quit; } else { }) Michael S <already5chosen@yahoo.com> - 2025-05-04 18:08 +0300
    Re: Loops (was Re: do { quit; } else { }) Michael S <already5chosen@yahoo.com> - 2025-05-05 10:42 +0300
    Re: Loops (was Re: do { quit; } else { }) Tim Rentsch <tr.17687@z991.linuxsc.com> - 2025-05-10 06:43 -0700
      Re: Loops (was Re: do { quit; } else { }) Muttley@dastardlyhq.com - 2025-05-10 15:56 +0000
        Re: Loops (was Re: do { quit; } else { }) scott@slp53.sl.home (Scott Lurndal) - 2025-05-10 17:48 +0000
          Re: Loops (was Re: do { quit; } else { }) Muttley@dastardlyhq.com - 2025-05-11 08:20 +0000
        Re: Loops (was Re: do { quit; } else { }) Tim Rentsch <tr.17687@z991.linuxsc.com> - 2025-05-10 14:29 -0700
          Re: Loops (was Re: do { quit; } else { }) Muttley@dastardlyhq.com - 2025-05-11 08:21 +0000
            Re: Loops (was Re: do { quit; } else { }) David Brown <david.brown@hesbynett.no> - 2025-05-11 12:02 +0200
              Re: Loops (was Re: do { quit; } else { }) Muttley@dastardlyhq.com - 2025-05-11 15:30 +0000
                Re: Loops (was Re: do { quit; } else { }) scott@slp53.sl.home (Scott Lurndal) - 2025-05-11 16:29 +0000
                Re: Loops (was Re: do { quit; } else { }) David Brown <david.brown@hesbynett.no> - 2025-05-11 18:49 +0200
              Re: Loops (was Re: do { quit; } else { }) Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2025-05-11 14:41 -0700
              Re: Loops (was Re: do { quit; } else { }) James Kuyper <jameskuyper@alumni.caltech.edu> - 2025-05-11 17:43 -0400
                Re: Loops (was Re: do { quit; } else { }) Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2025-05-11 15:06 -0700
                Re: Loops (was Re: do { quit; } else { }) James Kuyper <jameskuyper@alumni.caltech.edu> - 2025-05-11 18:30 -0400
                Re: Loops (was Re: do { quit; } else { }) Tim Rentsch <tr.17687@z991.linuxsc.com> - 2025-05-11 18:15 -0700
                Re: Loops (was Re: do { quit; } else { }) Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2025-05-11 19:09 -0700
                Re: Loops (was Re: do { quit; } else { }) Tim Rentsch <tr.17687@z991.linuxsc.com> - 2025-05-12 00:16 -0700
                Re: Loops (was Re: do { quit; } else { }) Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2025-05-12 02:23 -0700
                Re: Loops (was Re: do { quit; } else { }) Tim Rentsch <tr.17687@z991.linuxsc.com> - 2025-05-12 07:19 -0700
                Re: Loops (was Re: do { quit; } else { }) Richard Heathfield <rjh@cpax.org.uk> - 2025-05-12 15:34 +0100
                Re: Loops (was Re: do { quit; } else { }) Tim Rentsch <tr.17687@z991.linuxsc.com> - 2025-05-12 22:42 -0700
                Re: Loops (was Re: do { quit; } else { }) Richard Heathfield <rjh@cpax.org.uk> - 2025-05-13 07:31 +0100
                Re: Loops (was Re: do { quit; } else { }) Tim Rentsch <tr.17687@z991.linuxsc.com> - 2025-05-14 21:12 -0700
                Re: Loops (was Re: do { quit; } else { }) Tim Rentsch <tr.17687@z991.linuxsc.com> - 2025-05-13 09:30 -0700
                Re: Loops (was Re: do { quit; } else { }) Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2025-05-13 22:28 +0200
                Re: Loops (was Re: do { quit; } else { }) Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2025-05-12 13:31 -0700
                Re: Loops (was Re: do { quit; } else { }) Tim Rentsch <tr.17687@z991.linuxsc.com> - 2025-05-14 20:44 -0700
                Re: Loops (was Re: do { quit; } else { }) Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2025-05-14 21:45 -0700
                Re: Loops (was Re: do { quit; } else { }) David Brown <david.brown@hesbynett.no> - 2025-05-12 17:24 +0200
                Re: Loops (was Re: do { quit; } else { }) James Kuyper <jameskuyper@alumni.caltech.edu> - 2025-05-12 00:07 -0400
                Re: Loops (was Re: do { quit; } else { }) Tim Rentsch <tr.17687@z991.linuxsc.com> - 2025-05-12 00:43 -0700
                Re: Loops (was Re: do { quit; } else { }) Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2025-05-12 02:27 -0700
                Re: Loops (was Re: do { quit; } else { }) David Brown <david.brown@hesbynett.no> - 2025-05-12 17:18 +0200
                Re: Loops (was Re: do { quit; } else { }) James Kuyper <jameskuyper@alumni.caltech.edu> - 2025-05-12 19:53 -0400
                Re: Loops (was Re: do { quit; } else { }) Tim Rentsch <tr.17687@z991.linuxsc.com> - 2025-05-12 23:03 -0700
                Re: Loops (was Re: do { quit; } else { }) Tim Rentsch <tr.17687@z991.linuxsc.com> - 2025-05-12 19:04 -0700
                Re: Loops (was Re: do { quit; } else { }) David Brown <david.brown@hesbynett.no> - 2025-05-12 17:08 +0200
                Re: Loops (was Re: do { quit; } else { }) Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2025-05-12 13:38 -0700
                Re: Loops (was Re: do { quit; } else { }) David Brown <david.brown@hesbynett.no> - 2025-05-13 12:41 +0200
                Re: Loops (was Re: do { quit; } else { }) Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2025-05-13 23:16 +0200
                Re: Loops (was Re: do { quit; } else { }) Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2025-05-13 14:35 -0700
                Re: Loops (was Re: do { quit; } else { }) Tim Rentsch <tr.17687@z991.linuxsc.com> - 2025-05-13 15:10 -0700
                Re: Loops (was Re: do { quit; } else { }) Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2025-05-13 15:41 -0700
                Re: Loops (was Re: do { quit; } else { }) Tim Rentsch <tr.17687@z991.linuxsc.com> - 2025-05-13 18:38 -0700
                Re: Loops (was Re: do { quit; } else { }) Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2025-05-13 19:37 -0700
                Re: Loops (was Re: do { quit; } else { }) James Kuyper <jameskuyper@alumni.caltech.edu> - 2025-05-13 23:54 -0400
                Re: Loops (was Re: do { quit; } else { }) Tim Rentsch <tr.17687@z991.linuxsc.com> - 2025-05-13 21:19 -0700
                Re: Loops (was Re: do { quit; } else { }) Tim Rentsch <tr.17687@z991.linuxsc.com> - 2025-05-13 21:12 -0700
                Re: Loops (was Re: do { quit; } else { }) Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2025-05-13 22:38 -0700
                Re: Loops (was Re: do { quit; } else { }) Kaz Kylheku <643-408-1753@kylheku.com> - 2025-05-14 03:35 +0000
                Re: Loops (was Re: do { quit; } else { }) Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2025-05-13 21:54 -0700
                Re: Loops (was Re: do { quit; } else { }) Kaz Kylheku <643-408-1753@kylheku.com> - 2025-05-14 06:31 +0000
                Re: Loops (was Re: do { quit; } else { }) Tim Rentsch <tr.17687@z991.linuxsc.com> - 2025-06-10 06:01 -0700
                Re: Loops (was Re: do { quit; } else { }) Bonita Montero <Bonita.Montero@gmail.com> - 2025-06-14 12:24 +0200
                Re: Loops (was Re: do { quit; } else { }) scott@slp53.sl.home (Scott Lurndal) - 2025-06-14 13:57 +0000
                Re: Loops (was Re: do { quit; } else { }) Michael S <already5chosen@yahoo.com> - 2025-06-14 22:27 +0300
                Re: Loops (was Re: do { quit; } else { }) Bonita Montero <Bonita.Montero@gmail.com> - 2025-06-15 09:32 +0200
                Re: Loops (was Re: do { quit; } else { }) David Brown <david.brown@hesbynett.no> - 2025-05-14 13:00 +0200
                Re: Loops (was Re: do { quit; } else { }) Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2025-05-14 13:20 +0200
                Re: Loops (was Re: do { quit; } else { }) James Kuyper <jameskuyper@alumni.caltech.edu> - 2025-05-14 23:20 -0400
                Re: Loops (was Re: do { quit; } else { }) David Brown <david.brown@hesbynett.no> - 2025-05-15 11:23 +0200
            Re: Loops (was Re: do { quit; } else { }) Tim Rentsch <tr.17687@z991.linuxsc.com> - 2025-05-11 17:59 -0700
              Re: Loops (was Re: do { quit; } else { }) Muttley@DastardlyHQ.org - 2025-05-12 10:11 +0000
                Re: Loops (was Re: do { quit; } else { }) Michael S <already5chosen@yahoo.com> - 2025-05-12 17:09 +0300
      Re: Loops (was Re: do { quit; } else { }) Michael S <already5chosen@yahoo.com> - 2025-05-11 01:09 +0300
        Re: Loops (was Re: do { quit; } else { }) Tim Rentsch <tr.17687@z991.linuxsc.com> - 2025-05-11 17:30 -0700
          Re: Loops (was Re: do { quit; } else { }) Michael S <already5chosen@yahoo.com> - 2025-05-12 16:18 +0300
            Re: Loops (was Re: do { quit; } else { }) Tim Rentsch <tr.17687@z991.linuxsc.com> - 2025-05-14 11:09 -0700
          Re: Loops (was Re: do { quit; } else { }) Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2025-05-13 15:57 +0200
  Re: Loops (was Re: do { quit; } else { }) Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2025-05-04 13:52 -0700

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