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| From | James Harris <james.harris.1@gmail.com> |
|---|---|
| Newsgroups | comp.lang.c |
| Subject | Re: To include or not to include |
| Date | 2016-09-23 13:52 +0100 |
| Organization | A noiseless patient Spider |
| Message-ID | <ns38hm$54o$1@dont-email.me> (permalink) |
| References | <ns2tkb$p0$1@dont-email.me> <ns37a8$jj$1@dont-email.me> |
On 23/09/2016 13:31, Richard Heathfield wrote:
> On 23/09/16 10:45, James Harris wrote:
>> I often have at the top of a C source file, which I'll call F, an
>> include for its corresponding header:
>>
>> #include "F.h"
>>
>> After that come the various includes I need for the .c code that follows.
>>
>> In many cases the .c and the .h include some of the same files. They
>> might both pull in stdio.h or string.h, for example.
>>
>> Of course, I could omit from F.c at least some of the headers which F.h
>> includes. But I tend to take the approach of including in the .c all
>> those the .c code needs.
>
> So do I.
That's good enough for me.
>> Assuming either approach is just as valid, which is the best style or is
>> one more idiomatic than the other?
>
> If all the relevant headers are idempotent, then there is no technical
> reason not to include all the headers the source needs, in an explicit
> way. Thus, if we have:
>
> /* f.h */
> #ifndef F_H__
> #define F_H__ 1
> #include <stddef.h>
> typedef size_t SIZE;
> void *firstzerobyte(const void *vp, SIZE len);
> #endif
> /* end of f.h */
>
> /* f.c */
> #include "f.h"
> #include <stddef.h> /* whether to include this is the point at issue */
>
> void *firstzerobyte(const void *vp, SIZE len)
> {
> SIZE i = 0;
> unsigned char *p = vp;
> if(vp != NULL)
> {
> while(i < len && p[i] != '\0')
> {
> ++i;
> ++p;
> }
> }
> return p;
> }
> /* end of f.c */
>
> then I would argue that it's better explicitly to include <stddef.h> in
> f.c even though it's included in f.h. It adds a microscopic amount to
> the runtime of the pre-processor phase ("#ifndef - hmm, it's defined, so
> skip lightly through to the #endif'), and nothing to the runtime of the
> program itself, so where's the harm? And the benefit is that, if you
> later rip out the SIZE stuff, you don't have to stick back in all the
> includes you left out because f.h included them.
You've even gone beyond my original question! I have to say that, apart
from your use of NULL - for which I think stddef.h would be appropriate
- if the .c did not use size_t or anything else from stddef.h I would be
inclined not to include stddef.h in the .c file. ISTM that SIZE from f.h
would be enough. I am happy to be told that that is wrong but I cannot
see a reason to include that header if the code to follow did not make
any reference to anything defined therein.
--
James Harris
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To include or not to include James Harris <james.harris.1@gmail.com> - 2016-09-23 10:45 +0100
Re: To include or not to include David Brown <david.brown@hesbynett.no> - 2016-09-23 12:43 +0200
Re: To include or not to include BartC <bc@freeuk.com> - 2016-09-23 12:17 +0100
Re: To include or not to include Ben Bacarisse <ben.usenet@bsb.me.uk> - 2016-09-23 13:32 +0100
Re: To include or not to include David Brown <david.brown@hesbynett.no> - 2016-09-23 14:57 +0200
Re: To include or not to include BartC <bc@freeuk.com> - 2016-09-24 20:34 +0100
Re: To include or not to include Ben Bacarisse <ben.usenet@bsb.me.uk> - 2016-09-24 23:55 +0100
Re: To include or not to include BartC <bc@freeuk.com> - 2016-09-25 01:43 +0100
Re: To include or not to include Ian Collins <ian-news@hotmail.com> - 2016-09-25 14:38 +1300
Re: To include or not to include Ben Bacarisse <ben.usenet@bsb.me.uk> - 2016-09-25 11:42 +0100
Re: To include or not to include BartC <bc@freeuk.com> - 2016-09-25 11:58 +0100
Re: To include or not to include James Harris <james.harris.1@gmail.com> - 2016-09-25 14:06 +0100
Re: To include or not to include BartC <bc@freeuk.com> - 2016-09-25 15:15 +0100
Re: To include or not to include Reinhardt Behm <rbehm@hushmail.com> - 2016-09-25 23:33 +0800
Re: To include or not to include Joe Pfeiffer <pfeiffer@cs.nmsu.edu> - 2016-09-25 10:04 -0600
Re: To include or not to include Reinhardt Behm <rbehm@hushmail.com> - 2016-09-26 00:21 +0800
Re: To include or not to include "James R. Kuyper" <jameskuyper@verizon.net> - 2016-09-25 13:17 -0400
Re: To include or not to include James Harris <james.harris.1@gmail.com> - 2016-09-26 00:18 +0100
Re: To include or not to include BartC <bc@freeuk.com> - 2016-09-26 17:55 +0100
Re: To include or not to include Ben Bacarisse <ben.usenet@bsb.me.uk> - 2016-09-26 20:07 +0100
Re: To include or not to include supercat@casperkitty.com - 2016-09-26 12:13 -0700
Re: To include or not to include James Harris <james.harris.1@gmail.com> - 2016-09-27 01:25 +0100
Re: To include or not to include supercat@casperkitty.com - 2016-09-26 18:05 -0700
Re: To include or not to include Ben Bacarisse <ben.usenet@bsb.me.uk> - 2016-09-27 14:27 +0100
Re: To include or not to include BartC <bc@freeuk.com> - 2016-09-27 14:49 +0100
Re: To include or not to include Ben Bacarisse <ben.usenet@bsb.me.uk> - 2016-09-27 15:15 +0100
Re: To include or not to include Malcolm McLean <malcolm.mclean5@btinternet.com> - 2016-09-27 07:42 -0700
Re: To include or not to include Keith Thompson <kst-u@mib.org> - 2016-09-27 09:30 -0700
Re: To include or not to include Malcolm McLean <malcolm.mclean5@btinternet.com> - 2016-09-27 10:06 -0700
Re: To include or not to include supercat@casperkitty.com - 2016-09-27 08:12 -0700
Re: To include or not to include Tim Rentsch <txr@alumni.caltech.edu> - 2016-09-28 10:46 -0700
Re: To include or not to include BartC <bc@freeuk.com> - 2016-09-27 17:55 +0100
Re: To include or not to include supercat@casperkitty.com - 2016-09-27 10:19 -0700
Re: To include or not to include Keith Thompson <kst-u@mib.org> - 2016-09-27 11:42 -0700
Re: To include or not to include BartC <bc@freeuk.com> - 2016-09-27 19:57 +0100
Re: To include or not to include Keith Thompson <kst-u@mib.org> - 2016-09-27 12:38 -0700
Re: To include or not to include BartC <bc@freeuk.com> - 2016-09-27 21:00 +0100
Re: To include or not to include Ben Bacarisse <ben.usenet@bsb.me.uk> - 2016-09-28 01:50 +0100
Re: To include or not to include BartC <bc@freeuk.com> - 2016-09-28 10:55 +0100
Re: To include or not to include Malcolm McLean <malcolm.mclean5@btinternet.com> - 2016-09-27 13:33 -0700
Re: To include or not to include Ike Naar <ike@iceland.freeshell.org> - 2016-09-28 19:13 +0000
Re: To include or not to include supercat@casperkitty.com - 2016-09-27 12:38 -0700
Re: To include or not to include James Harris <james.harris.1@gmail.com> - 2016-09-27 20:57 +0100
Re: To include or not to include supercat@casperkitty.com - 2016-09-27 07:25 -0700
Re: To include or not to include Ben Bacarisse <ben.usenet@bsb.me.uk> - 2016-09-28 00:28 +0100
Re: To include or not to include supercat@casperkitty.com - 2016-09-30 07:53 -0700
Re: To include or not to include Ben Bacarisse <ben.usenet@bsb.me.uk> - 2016-09-30 16:06 +0100
Re: To include or not to include Ben Bacarisse <ben.usenet@bsb.me.uk> - 2016-09-27 13:53 +0100
Re: To include or not to include James Harris <james.harris.1@gmail.com> - 2016-09-30 19:46 +0100
Re: To include or not to include Ben Bacarisse <ben.usenet@bsb.me.uk> - 2016-09-30 20:27 +0100
Re: To include or not to include Reinhardt Behm <rbehm@hushmail.com> - 2016-09-25 23:27 +0800
Re: To include or not to include Jerry Stuckle <jstucklex@attglobal.net> - 2016-09-25 11:38 -0400
Re: To include or not to include Reinhardt Behm <rbehm@hushmail.com> - 2016-09-25 23:40 +0800
Re: To include or not to include BartC <bc@freeuk.com> - 2016-09-25 15:06 +0100
Re: To include or not to include Jerry Stuckle <jstucklex@attglobal.net> - 2016-09-25 11:49 -0400
Re: To include or not to include BartC <bc@freeuk.com> - 2016-09-25 18:05 +0100
Re: To include or not to include Jerry Stuckle <jstucklex@attglobal.net> - 2016-09-25 16:42 -0400
Re: To include or not to include BartC <bc@freeuk.com> - 2016-09-25 21:53 +0100
Re: To include or not to include Jerry Stuckle <jstucklex@attglobal.net> - 2016-09-25 17:57 -0400
Re: To include or not to include Ben Bacarisse <ben.usenet@bsb.me.uk> - 2016-09-25 21:20 +0100
Re: To include or not to include BartC <bc@freeuk.com> - 2016-09-25 21:49 +0100
Re: To include or not to include Ben Bacarisse <ben.usenet@bsb.me.uk> - 2016-09-26 00:40 +0100
Re: To include or not to include David Brown <david.brown@hesbynett.no> - 2016-09-23 14:56 +0200
Re: To include or not to include Richard Heathfield <rjh@cpax.org.uk> - 2016-09-23 13:31 +0100
Re: To include or not to include James Harris <james.harris.1@gmail.com> - 2016-09-23 13:52 +0100
Re: To include or not to include Richard Heathfield <rjh@cpax.org.uk> - 2016-09-23 14:35 +0100
Re: To include or not to include Ben Bacarisse <ben.usenet@bsb.me.uk> - 2016-09-23 18:55 +0100
Re: To include or not to include Richard Heathfield <rjh@cpax.org.uk> - 2016-09-23 20:33 +0100
Re: To include or not to include Joe Pfeiffer <pfeiffer@cs.nmsu.edu> - 2016-09-23 08:22 -0600
Re: To include or not to include Richard Damon <Richard@Damon-Family.org> - 2016-09-23 11:37 -0400
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