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Groups > comp.lang.c > #162227
| From | Manfred <noname@add.invalid> |
|---|---|
| Newsgroups | comp.lang.c |
| Subject | Re: Padding between char array/VLA in struct? |
| Date | 2021-08-04 17:01 +0200 |
| Organization | Aioe.org NNTP Server |
| Message-ID | <seea3q$7a6$1@gioia.aioe.org> (permalink) |
| References | <se9b5g$l2n$1@dont-email.me> <se9fa1$ikv$1@dont-email.me> <87sfzr8umf.fsf@nosuchdomain.example.com> |
On 8/2/2021 10:22 PM, Keith Thompson wrote:
> Ian Pilcher <arequipeno@gmail.com> writes:
>> On 8/2/21 12:48 PM, Ian Pilcher wrote:
>>> Given the following:
>>> struct foo {
>>> /* other members */
>>> char prefix[PREFIX_SIZE];
>>> char name[];
>>> };
>>
>> As has been pointed out, the 'name' member is a flexible array member,
>> not a variable length array. I apologize for the mistake.
>>
>> Also, PREFIX_SIZE is intended to represent a macro that expands to a
>> positive(!) integer constant expression.
>>
>> The consensus seems to be that no one can think of a good reason that a
>> compiler would insert padding between the 'prefix' and 'name' members,
>> but there's nothing in any of the language standards that would forbid
>> it from doing so. That would certainly explain my failure to find any
>> such rule.
>>
>> (_Static_assert here I come!)
>
> The ABI for whatever target platform you're interested in might have
> something to say about it.
It may be worth pointing out that ABIs set requirements for exported
interfaces - they don't pose restrictions to compilers for accesses to
local data and functions.
>
> (I can imagine that some compiler might find it convenient to give the
> name[] member an alignment stricter than 1 byte.)
>
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Padding between char array/VLA in struct? Ian Pilcher <arequipeno@gmail.com> - 2021-08-02 12:48 -0500
Re: Padding between char array/VLA in struct? James Kuyper <jameskuyper@alumni.caltech.edu> - 2021-08-02 14:07 -0400
Re: Padding between char array/VLA in struct? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2021-08-02 11:25 -0700
Re: Padding between char array/VLA in struct? James Kuyper <jameskuyper@alumni.caltech.edu> - 2021-08-02 19:21 -0400
Re: Padding between char array/VLA in struct? Bart <bc@freeuk.com> - 2021-08-02 19:11 +0100
Re: Padding between char array/VLA in struct? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2021-08-02 11:27 -0700
Re: Padding between char array/VLA in struct? Bart <bc@freeuk.com> - 2021-08-02 20:43 +0100
Re: Padding between char array/VLA in struct? Andrey Tarasevich <andreytarasevich@hotmail.com> - 2021-08-02 13:11 -0700
Re: Padding between char array/VLA in struct? Andrey Tarasevich <andreytarasevich@hotmail.com> - 2021-08-02 13:18 -0700
Re: Padding between char array/VLA in struct? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2021-08-02 13:31 -0700
Re: Padding between char array/VLA in struct? Andrey Tarasevich <andreytarasevich@hotmail.com> - 2021-08-02 19:50 -0700
Re: Padding between char array/VLA in struct? David Brown <david.brown@hesbynett.no> - 2021-08-04 14:01 +0200
Re: Padding between char array/VLA in struct? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2021-08-02 13:19 -0700
Re: Padding between char array/VLA in struct? BGB <cr88192@gmail.com> - 2021-08-03 10:40 -0500
Re: Padding between char array/VLA in struct? Andrey Tarasevich <andreytarasevich@hotmail.com> - 2021-08-03 09:10 -0700
Re: Padding between char array/VLA in struct? BGB <cr88192@gmail.com> - 2021-08-03 12:52 -0500
Re: Padding between char array/VLA in struct? BGB <cr88192@gmail.com> - 2021-08-04 12:05 -0500
Re: Padding between char array/VLA in struct? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2021-08-02 11:12 -0700
Re: Padding between char array/VLA in struct? Bart <bc@freeuk.com> - 2021-08-02 19:23 +0100
Re: Padding between char array/VLA in struct? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2021-08-02 13:15 -0700
Re: Padding between char array/VLA in struct? Andrey Tarasevich <andreytarasevich@hotmail.com> - 2021-08-02 11:32 -0700
Re: Padding between char array/VLA in struct? Ian Pilcher <arequipeno@gmail.com> - 2021-08-02 13:59 -0500
Re: Padding between char array/VLA in struct? Tim Rentsch <tr.17687@z991.linuxsc.com> - 2021-08-02 12:47 -0700
Re: Padding between char array/VLA in struct? Ian Pilcher <arequipeno@gmail.com> - 2021-08-02 15:27 -0500
Re: Padding between char array/VLA in struct? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2021-08-02 13:36 -0700
Re: Padding between char array/VLA in struct? antispam@math.uni.wroc.pl - 2021-08-02 21:52 +0000
Re: Padding between char array/VLA in struct? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2021-08-02 13:22 -0700
Re: Padding between char array/VLA in struct? Manfred <noname@add.invalid> - 2021-08-04 17:01 +0200
Re: Padding between char array/VLA in struct? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2021-08-04 10:11 -0700
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