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Groups > comp.lang.c > #383586
| From | Keith Thompson <Keith.S.Thompson+u@gmail.com> |
|---|---|
| Newsgroups | comp.lang.c |
| Subject | Re: Word For Today: “Uglification” |
| Date | 2024-03-13 09:03 -0700 |
| Organization | None to speak of |
| Message-ID | <877ci66rvk.fsf@nosuchdomain.example.com> (permalink) |
| References | (9 earlier) <uspt5n$c2bg$1@dont-email.me> <20240312114213.182@kylheku.com> <usql0p$hk2k$1@dont-email.me> <878r2n839m.fsf@nosuchdomain.example.com> <uss3kr$ud17$1@dont-email.me> |
bart <bc@freeuk.com> writes:
> On 12/03/2024 23:00, Keith Thompson wrote:
>> bart <bc@freeuk.com> writes:
>>> That is undesirable, unless you specifically want to shadow the
>>> standard headers. In the examples I saw, that was not the case.
>> You didn't mention that. If you'd tell us what project you're
>> talking about, maybe we could discuss it. Perhaps
>
> That's not really relevant. Suffice that they are amateur projects and
> clearly they were using using string.h etc for their own purposes
> without thinking.
As far as I can tell from what you've written, they may have been using
"string.h" correctly, as a local file that's part of the project.
>> Read section 6.10.2 of the standard. It describes the search rules for
>> the #include directive.
>
> Not in N1570 it doesn't. It seems mainly concerned with the syntax.
"""
A preprocessing directive of the form
# include <h-char-sequence> new-line
searches a sequence of implementation-defined places for a header
identified uniquely by the specified sequence between the < and >
delimiters,
"""
and so on. That's what I meant when I said it describes the search
rules. It doesn't completely define them.
> I understand that the algorithm for finding include files was
> implementation-defined, and typically depended on these inputs:
>
> * Whether the filename used "..." or <...>
> * Whether the file-name specified was absolute or relative
> * The path of the source file in which the #include occurs
> * Possibly, the complete stack of paths for the current sequence set of
> nested #includes
> * Possibly, on the CWD
> * On where the compiler keeps its standard headers (which in turn may
> depend on OS)
> * On the set of -I directives given to the compiler (this is
> something outside the remit of the standard, AIUI)
Yes -- but you left out a major part of it, that if a search for a ""
header fails, it continues by treating it as if it were a <> header.
Thus #include "stdio.h" will use a header file by that name if it
exists, and is equivalent to #include <stdio.h> otherwise.
>> To summarize, #include <foo.h> searches for a header (probably but
>> not necessarily a file) identified by foo.h. #include "foo.h"
>> searches for a *file* called foo.h, and if that fails it then
>> searches for a header identified by <foo.h>. The sequences for both
>> searches are implementation-defined.
>
> This is something new I saw today: suppose I have hello.c in a
> directory (hello.c uses '#include <stdio.h>').
>
> If I create an empty file called 'stdio.h', then 4 compilers I tried
> all picked up that file instead of their official stdio.h. That looks
> a dangerous practice to me.
If they're behaving as you're describing, then they're not conforming.
I've tried gcc, clang, and tcc, and all pick up the correct <stdio.h>
header even if there's a "stdio.h" file in the current directory.
It's possible in principle that a compiler could include the current
directory in the <> search path, but that would be surprising, and none
of the compilers I've tried do so.
What are these 4 compilers? Are you sure you used <stdio.h> and not
"stdio.h"? Did you use any additional command line options? Might you
have set some environment variable like $C_INCLUDE PATH that affects the
behavior?
> It also seems, for a <...> file, to ignore the official repository and
> look first within the user's project. So what exactly is the
> difference between <...> and "..."? Is it just an extra set of backup
> paths to look if it can't find anything within the user's files?
The difference is as I've described above.
> (The 5th compiler I tried ignored it and worked as normal; that was
> mine. I can make it fail using my '-ext' option to look elsewhere than
> the official headers location. I don't make a distinction between
> <...> and "...".)
Perhaps I'm missing something. If your compiler doesn't distinguish
between <> and "", then #include "stdio.h" should be equivalent to
#include <stdio.h>. You say it ignores a stdio.h file in the current
directory. Then how can a source file include *any* header file in the
current directory?
#include <stdio.h> // This includes the system header.
#include "stdio.h" // You say this ignores any local file and
// includes the system header.
#include "foo.h" // Does this not include a local file named "foo.h"?
--
Keith Thompson (The_Other_Keith) Keith.S.Thompson+u@gmail.com
Working, but not speaking, for Medtronic
void Void(void) { Void(); } /* The recursive call of the void */
Back to comp.lang.c | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread
Word For Today: “Uglification” Lawrence D'Oliveiro <ldo@nz.invalid> - 2024-03-12 00:14 +0000
Re: Word For Today: “Uglification” Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2024-03-11 18:15 -0700
Re: Word For Today: “Uglification” Lawrence D'Oliveiro <ldo@nz.invalid> - 2024-03-12 01:34 +0000
Re: Word For Today: “Uglification” Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2024-03-11 19:56 -0700
Re: Word For Today: “Uglification” Kaz Kylheku <433-929-6894@kylheku.com> - 2024-03-12 03:30 +0000
Re: Word For Today: “Uglification” Tim Rentsch <tr.17687@z991.linuxsc.com> - 2024-03-14 10:23 -0700
Re: Word For Today: “Uglification” Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2024-03-14 14:31 -0700
Re: Word For Today: “Uglification” scott@slp53.sl.home (Scott Lurndal) - 2024-03-14 23:59 +0000
Re: Word For Today: “Uglification” scott@slp53.sl.home (Scott Lurndal) - 2024-03-15 00:01 +0000
Re: Word For Today: “Uglification” Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2024-03-14 17:11 -0700
Re: Word For Today: “Uglification” scott@slp53.sl.home (Scott Lurndal) - 2024-03-15 00:33 +0000
Re: Word For Today: “Uglification” David Brown <david.brown@hesbynett.no> - 2024-03-15 09:15 +0100
Re: Word For Today: “Uglification” Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2024-03-14 17:15 -0700
Re: Word For Today: “Uglification” scott@slp53.sl.home (Scott Lurndal) - 2024-03-15 00:34 +0000
Re: Word For Today: “Uglification” Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2024-03-14 19:19 -0700
Re: Word For Today: “Uglification” Kaz Kylheku <433-929-6894@kylheku.com> - 2024-03-15 03:17 +0000
Re: Word For Today: “Uglification” Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2024-03-14 20:44 -0700
Re: Word For Today: “Uglification” David Brown <david.brown@hesbynett.no> - 2024-03-15 09:22 +0100
Re: Word For Today: “Uglification” Tim Rentsch <tr.17687@z991.linuxsc.com> - 2024-03-14 19:49 -0700
Re: Word For Today: “Uglification” James Kuyper <jameskuyper@alumni.caltech.edu> - 2024-03-12 01:33 -0400
Re: Word For Today: “Uglification” Lawrence D'Oliveiro <ldo@nz.invalid> - 2024-03-12 06:14 +0000
Re: Word For Today: “Uglification” Lawrence D'Oliveiro <ldo@nz.invalid> - 2024-03-12 06:21 +0000
Re: Word For Today: “Uglification” Kaz Kylheku <433-929-6894@kylheku.com> - 2024-03-12 07:44 +0000
Re: Word For Today: “Uglification” Richard Kettlewell <invalid@invalid.invalid> - 2024-03-12 08:03 +0000
Re: Word For Today: “Uglification” David Brown <david.brown@hesbynett.no> - 2024-03-12 11:10 +0100
Re: Word For Today: “Uglification” Anton Shepelev <anton.txt@g{oogle}mail.com> - 2024-03-12 17:46 +0300
Re: Word For Today: “Uglification” bart <bc@freeuk.com> - 2024-03-12 14:53 +0000
Re: Word For Today: “Uglification” Anton Shepelev <anton.txt@g{oogle}mail.com> - 2024-03-12 18:09 +0300
Re: Word For Today: “Uglification” bart <bc@freeuk.com> - 2024-03-12 15:42 +0000
Re: Word For Today: “Uglification” Kaz Kylheku <433-929-6894@kylheku.com> - 2024-03-12 18:50 +0000
Re: Word For Today: “Uglification” bart <bc@freeuk.com> - 2024-03-12 22:29 +0000
Re: Word For Today: “Uglification” Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2024-03-12 16:00 -0700
Re: Word For Today: “Uglification” bart <bc@freeuk.com> - 2024-03-13 11:45 +0000
Re: Word For Today: “Uglification” Michael S <already5chosen@yahoo.com> - 2024-03-13 14:12 +0200
Re: Word For Today: “Uglification” Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2024-03-13 08:15 -0700
Re: Word For Today: “Uglification” David Brown <david.brown@hesbynett.no> - 2024-03-13 18:47 +0100
Re: Word For Today: “Uglification” Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2024-03-13 11:56 -0700
Re: Word For Today: “Uglification” David Brown <david.brown@hesbynett.no> - 2024-03-13 22:07 +0100
Re: Word For Today: “Uglification” David Brown <david.brown@hesbynett.no> - 2024-03-13 16:40 +0100
Re: Word For Today: “Uglification” Kaz Kylheku <433-929-6894@kylheku.com> - 2024-03-13 15:48 +0000
Re: Word For Today: “Uglification” Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2024-03-13 09:03 -0700
Re: Word For Today: “Uglification” bart <bc@freeuk.com> - 2024-03-13 16:44 +0000
Re: Word For Today: “Uglification” Nick Bowler <nbowler@draconx.ca> - 2024-03-13 17:01 +0000
Re: Word For Today: “Uglification” Kaz Kylheku <433-929-6894@kylheku.com> - 2024-03-13 02:53 +0000
Re: Word For Today: “Uglification” Kaz Kylheku <433-929-6894@kylheku.com> - 2024-03-12 18:42 +0000
Re: Word For Today: “Uglification” Blue-Maned_Hawk <bluemanedhawk@invalid.invalid> - 2024-03-12 22:07 +0000
Re: Word For Today: “Uglification” Lawrence D'Oliveiro <ldo@nz.invalid> - 2024-03-12 23:13 +0000
Re: Word For Today: “Uglification” Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2024-03-12 16:29 -0700
Re: Word For Today: “Uglification” Richard Kettlewell <invalid@invalid.invalid> - 2024-03-13 09:01 +0000
Re: Word For Today: “Uglification” Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2024-03-13 08:06 -0700
Re: Word For Today: “Uglification” Lawrence D'Oliveiro <ldo@nz.invalid> - 2024-03-13 21:51 +0000
Re: Word For Today: “Uglification” Kaz Kylheku <433-929-6894@kylheku.com> - 2024-03-13 22:16 +0000
Re: Word For Today: “Uglification” Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2024-03-13 15:26 -0700
Re: Word For Today: “Uglification” scott@slp53.sl.home (Scott Lurndal) - 2024-03-13 22:33 +0000
Re: Word For Today: “Uglification” Lawrence D'Oliveiro <ldo@nz.invalid> - 2024-03-13 22:50 +0000
Re: Word For Today: “Uglification” Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2024-03-13 16:06 -0700
Re: Word For Today: “Uglification” Richard Kettlewell <invalid@invalid.invalid> - 2024-03-13 23:32 +0000
Re: Word For Today: “Uglification” Kaz Kylheku <433-929-6894@kylheku.com> - 2024-03-14 00:40 +0000
Re: Word For Today: “Uglification” scott@slp53.sl.home (Scott Lurndal) - 2024-03-13 23:15 +0000
Re: Word For Today: “Uglification” Tim Rentsch <tr.17687@z991.linuxsc.com> - 2024-06-18 23:09 -0700
Re: Word For Today: “Uglification” Kaz Kylheku <433-929-6894@kylheku.com> - 2024-03-13 00:23 +0000
Re: Word For Today: “Uglification” James Kuyper <jameskuyper@alumni.caltech.edu> - 2024-03-12 11:51 -0400
Re: Word For Today: “Uglification” Lawrence D'Oliveiro <ldo@nz.invalid> - 2024-03-12 21:31 +0000
Re: Word For Today: “Uglification” Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2024-03-12 15:21 -0700
Re: Word For Today: “Uglification” James Kuyper <jameskuyper@alumni.caltech.edu> - 2024-03-13 03:36 -0400
Re: Word For Today: “Uglification” Lawrence D'Oliveiro <ldo@nz.invalid> - 2024-03-13 21:52 +0000
Re: Word For Today: “Uglification” Kaz Kylheku <433-929-6894@kylheku.com> - 2024-03-13 22:10 +0000
Re: Word For Today: “Uglification” James Kuyper <jameskuyper@alumni.caltech.edu> - 2024-03-13 20:47 -0400
Re: Word For Today: “Uglification” Kaz Kylheku <433-929-6894@kylheku.com> - 2024-03-12 06:15 +0000
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