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Groups > comp.lang.c > #397303
| From | Tim Rentsch <tr.17687@z991.linuxsc.com> |
|---|---|
| Newsgroups | comp.lang.c |
| Subject | Re: gcc and 'include' |
| Date | 2026-03-30 05:33 -0700 |
| Organization | A noiseless patient Spider |
| Message-ID | <86mrzp1oql.fsf@linuxsc.com> (permalink) |
| References | (4 earlier) <10q6uv4$419b$1@dont-email.me> <20260328203718.00005c70@yahoo.com> <10q96uf$rjbn$1@dont-email.me> <10q9t6d$2p36t$1@paganini.bofh.team> <10qc632$1uds9$1@dont-email.me> |
Bart <bc@freeuk.com> writes: > On 29/03/2026 00:53, Waldek Hebisch wrote: > >> Bart <bc@freeuk.com> wrote: >> >>> That you declare 'abc' as something to be imported, yet in the next line >>> it is initialised as though it was exported. >> >> Well, C is not able to directy express notion of export and import. >> Also, C does not have modules/interfaces etc. Instead C object >> may be global (which is specified by 'extern' or by lack of storage >> class at file scope) or local. C rules allow you to emulate >> modules using header files. Namely, in header file you put >> 'extern' declaration for exports of given module. Any user of >> of the module must include the corresponding header file. >> To ensure consistency also implementation of the module should >> include the header file. So everywhere elso you have just >> 'extern' declaration, but in implementation there is 'extern' >> declaration first followed by the definition. If such >> sequence was disallowed, then it would be harder to check >> consistency of implementation and corresponding header. >> >> So in reasonable code 'extern' really means "part of interface" >> without specifying if it is import or export. > > But, the rules are lax, and implementations exploit that by all > behaving a little differently. The rules are not lax; they are carefully and precisely defined. To see that one needs to know what the rules are, which in turn depends on reading and understanding the C standard. > TBF, the diverse implementations probably came first, and the > standard had to accommodate existing practice. Diverse implementations certainly came first, including especially the original description of C in "The C Programming Language", by Kernighan and Ritchie. The rules for global symbols in K&R C are markedly different than those in the current C standard. There is a long explanation of different options considered for standard C, given in the C Rationale document.
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gcc and 'include' Bart <bc@freeuk.com> - 2026-03-26 22:36 +0000
Re: gcc and 'include' Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2026-03-26 16:12 -0700
Re: gcc and 'include' Bart <bc@freeuk.com> - 2026-03-27 10:55 +0000
Re: gcc and 'include' David Brown <david.brown@hesbynett.no> - 2026-03-27 13:49 +0100
Re: gcc and 'include' Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2026-03-27 10:51 -0700
Re: gcc and 'include' Tim Rentsch <tr.17687@z991.linuxsc.com> - 2026-04-25 10:09 -0700
Re: gcc and 'include' Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2026-04-25 15:58 -0700
Re: gcc and 'include' Lawrence D’Oliveiro <ldo@nz.invalid> - 2026-03-27 21:27 +0000
Re: gcc and 'include' Bart <bc@freeuk.com> - 2026-03-27 22:05 +0000
Re: gcc and 'include' Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2026-03-27 17:03 -0700
Re: gcc and 'include' Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2026-03-28 05:10 +0100
Re: gcc and 'include' Michael S <already5chosen@yahoo.com> - 2026-03-28 20:37 +0300
Re: gcc and 'include' Bart <bc@freeuk.com> - 2026-03-28 18:33 +0000
Re: gcc and 'include' antispam@fricas.org (Waldek Hebisch) - 2026-03-29 00:53 +0000
Re: gcc and 'include' Bart <bc@freeuk.com> - 2026-03-29 22:37 +0100
Re: gcc and 'include' Tim Rentsch <tr.17687@z991.linuxsc.com> - 2026-03-30 05:33 -0700
Re: gcc and 'include' Bart <bc@freeuk.com> - 2026-03-30 14:42 +0100
Re: gcc and 'include' Michael S <already5chosen@yahoo.com> - 2026-03-30 16:53 +0300
Re: gcc and 'include' Bart <bc@freeuk.com> - 2026-03-30 18:11 +0100
Re: gcc and 'include' Tim Rentsch <tr.17687@z991.linuxsc.com> - 2026-03-30 08:27 -0700
Re: gcc and 'include' Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2026-03-30 11:54 -0700
Re: gcc and 'include' Bart <bc@freeuk.com> - 2026-03-30 21:54 +0100
Re: gcc and 'include' Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2026-03-30 18:07 -0700
Re: gcc and 'include' Bart <bc@freeuk.com> - 2026-03-31 11:39 +0100
Re: gcc and 'include' Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2026-03-31 13:56 -0700
Re: gcc and 'include' Tim Rentsch <tr.17687@z991.linuxsc.com> - 2026-04-06 20:56 -0700
Re: gcc and 'include' Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2026-04-06 23:12 -0700
Re: gcc and 'include' James Kuyper <jameskuyper@alumni.caltech.edu> - 2026-03-30 21:06 -0400
Re: gcc and 'include' David Brown <david.brown@hesbynett.no> - 2026-03-29 11:24 +0200
Re: gcc and 'include' Bart <bc@freeuk.com> - 2026-03-29 12:44 +0100
Re: gcc and 'include' David Brown <david.brown@hesbynett.no> - 2026-03-31 15:57 +0200
Re: gcc and 'include' Tim Rentsch <tr.17687@z991.linuxsc.com> - 2026-03-30 07:20 -0700
Re: gcc and 'include' Tim Rentsch <tr.17687@z991.linuxsc.com> - 2026-03-30 05:07 -0700
Re: gcc and 'include' Lawrence D’Oliveiro <ldo@nz.invalid> - 2026-03-27 00:25 +0000
Re: gcc and 'include' Lawrence D’Oliveiro <ldo@nz.invalid> - 2026-03-30 07:13 +0000
Re: gcc and 'include' Andrey Tarasevich <noone@noone.net> - 2026-03-30 07:54 -0700
Re: gcc and 'include' Lawrence D’Oliveiro <ldo@nz.invalid> - 2026-03-31 01:46 +0000
Re: gcc and 'include' antispam@fricas.org (Waldek Hebisch) - 2026-03-31 05:28 +0000
Re: gcc and 'include' Michael S <already5chosen@yahoo.com> - 2026-03-27 04:10 +0300
Re: gcc and 'include' Tim Rentsch <tr.17687@z991.linuxsc.com> - 2026-03-26 19:08 -0700
Re: gcc and 'include' Michael S <already5chosen@yahoo.com> - 2026-03-27 16:47 +0300
Re: gcc and 'include' David Brown <david.brown@hesbynett.no> - 2026-03-27 16:43 +0100
Re: gcc and 'include' Tim Rentsch <tr.17687@z991.linuxsc.com> - 2026-03-27 09:03 -0700
Re: gcc and 'include' Michael S <already5chosen@yahoo.com> - 2026-03-29 11:46 +0300
Re: gcc and 'include' Tim Rentsch <tr.17687@z991.linuxsc.com> - 2026-03-30 08:19 -0700
Re: gcc and 'include' Michael S <already5chosen@yahoo.com> - 2026-03-30 20:08 +0300
Re: gcc and 'include' Tim Rentsch <tr.17687@z991.linuxsc.com> - 2026-03-31 00:26 -0700
Re: gcc and 'include' Michael S <already5chosen@yahoo.com> - 2026-03-31 11:27 +0300
Re: gcc and 'include' Tim Rentsch <tr.17687@z991.linuxsc.com> - 2026-04-07 09:45 -0700
Re: gcc and 'include' Andrey Tarasevich <noone@noone.net> - 2026-03-28 10:25 -0700
Re: gcc and 'include' Michael S <already5chosen@yahoo.com> - 2026-03-29 10:37 +0300
Re: gcc and 'include' David Brown <david.brown@hesbynett.no> - 2026-03-29 11:30 +0200
Re: gcc and 'include' Andrey Tarasevich <noone@noone.net> - 2026-03-29 07:22 -0700
Re: gcc and 'include' James Kuyper <jameskuyper@alumni.caltech.edu> - 2026-03-29 13:56 -0400
Re: gcc and 'include' Michael S <already5chosen@yahoo.com> - 2026-03-29 21:39 +0300
Re: gcc and 'include' James Kuyper <jameskuyper@alumni.caltech.edu> - 2026-03-29 20:08 -0400
Re: gcc and 'include' Bart <bc@freeuk.com> - 2026-03-30 01:58 +0100
Re: gcc and 'include' Tim Rentsch <tr.17687@z991.linuxsc.com> - 2026-03-30 07:59 -0700
Re: gcc and 'include' Tim Rentsch <tr.17687@z991.linuxsc.com> - 2026-03-26 19:06 -0700
Re: gcc and 'include' Bart <bc@freeuk.com> - 2026-03-27 16:20 +0000
Re: gcc and 'include' David Brown <david.brown@hesbynett.no> - 2026-03-27 18:07 +0100
Re: gcc and 'include' James Kuyper <jameskuyper@alumni.caltech.edu> - 2026-03-28 18:48 -0400
Re: gcc and 'include' Andrey Tarasevich <noone@noone.net> - 2026-03-27 22:38 -0700
Re: gcc and 'include' Tim Rentsch <tr.17687@z991.linuxsc.com> - 2026-03-28 00:30 -0700
Re: gcc and 'include' Andrey Tarasevich <noone@noone.net> - 2026-03-29 16:15 -0700
Re: gcc and 'include' Tim Rentsch <tr.17687@z991.linuxsc.com> - 2026-03-30 00:41 -0700
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