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| From | Keith Thompson <kst-u@mib.org> |
|---|---|
| Newsgroups | comp.lang.c |
| Subject | Re: Reading beyond the end of file |
| Date | 2015-10-05 15:24 -0700 |
| Organization | None to speak of |
| Message-ID | <lnpp0t3qdk.fsf@kst-u.example.com> (permalink) |
| References | (10 earlier) <musu7o$v4j$1@speranza.aioe.org> <lnio6l6gch.fsf@kst-u.example.com> <muthba$83c$1@speranza.aioe.org> <lntwq53zw4.fsf@kst-u.example.com> <a6fd81a8-4754-4a20-be95-ce17f23738b9@googlegroups.com> |
supercat@casperkitty.com writes:
> On Monday, October 5, 2015 at 1:59:45 PM UTC-5, Keith Thompson wrote:
>> Another problem is that the input character is treated as an unsigned
>> char and converted to signed int. If unsigned char fits in the range of
>> signed int, that's not a problem. But if not, and if you read a
>> character with a value exceeding INT_MAX, then the conversion to int
>> yields an implementation-defined result or raises an
>> implementation-defined signal. Probably the conversion will do the
>> typical 2's-complement wraparound, but if it doesn't, hilarity ensues.
>
> If James Kuyper's citation of 7.21.2p3 is accurate, I would think that any
> platform where UCHAR_MAX > INT_MAX would be required to use an "int" type
> which supported a value which behaved as -INT_MAX-1. I think it might be
> possible for a ones'-complement or sign-magnitude implementation to meet
> the requirement if the bit pattern for "negative zero" was never generated
> by any calculations within the range of "int" but was produced by trying to
> convert "INT_MAX+1U" to "int", and if converting that value to "unsigned"
> yielded "INT_MAX+1U".
Yes, James raised some points that I hadn't thought of. The required
behavior for stdio seems to impose some additional requirements on how
certain integer conversions behave.
Note that that's relevant only for implementations with UCHAR_MAX >
INT_MAX. As I mentioned elsethread, there are currently very few such
impementations, and as far as I know they're all freestanding (which
means they needn't support stdio, which means the additional requirement
don't apply.)
--
Keith Thompson (The_Other_Keith) kst-u@mib.org <http://www.ghoti.net/~kst>
Working, but not speaking, for JetHead Development, Inc.
"We must do something. This is something. Therefore, we must do this."
-- Antony Jay and Jonathan Lynn, "Yes Minister"
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Re: Reading beyond the end of file Tim Rentsch <txr@alumni.caltech.edu> - 2015-09-11 10:06 -0700
Re: Reading beyond the end of file Geoff <geoff@invalid.invalid> - 2015-09-11 12:41 -0700
Re: Reading beyond the end of file Tim Rentsch <txr@alumni.caltech.edu> - 2015-09-26 14:24 -0700
Re: Reading beyond the end of file Geoff <geoff@invalid.invalid> - 2015-09-26 21:49 -0700
Re: Reading beyond the end of file Tim Rentsch <txr@alumni.caltech.edu> - 2015-10-01 13:57 -0700
Re: Reading beyond the end of file Geoff <geoff@invalid.invalid> - 2015-10-01 17:22 -0700
Re: Reading beyond the end of file raltbos@xs4all.nl (Richard Bos) - 2015-10-02 13:05 +0000
Re: Reading beyond the end of file Tim Rentsch <txr@alumni.caltech.edu> - 2015-10-04 17:56 -0700
Re: Reading beyond the end of file Joe Pfeiffer <pfeiffer@cs.nmsu.edu> - 2015-09-11 13:55 -0600
Re: Reading beyond the end of file Tim Rentsch <txr@alumni.caltech.edu> - 2015-09-26 14:14 -0700
Re: Reading beyond the end of file Siri Cruz <chine.bleu@yahoo.com> - 2015-09-26 14:43 -0700
Re: Reading beyond the end of file Lew Pitcher <lew.pitcher@digitalfreehold.ca> - 2015-09-26 17:57 -0400
Re: Reading beyond the end of file Tim Rentsch <txr@alumni.caltech.edu> - 2015-10-01 14:01 -0700
Re: Reading beyond the end of file Joe Pfeiffer <pfeiffer@cs.nmsu.edu> - 2015-09-26 22:18 -0600
Re: Reading beyond the end of file Tim Rentsch <txr@alumni.caltech.edu> - 2015-10-01 12:58 -0700
Re: Reading beyond the end of file Joe Pfeiffer <pfeiffer@cs.nmsu.edu> - 2015-10-01 15:08 -0600
Re: Reading beyond the end of file Tim Rentsch <txr@alumni.caltech.edu> - 2015-10-04 18:03 -0700
Re: Reading beyond the end of file glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2015-10-05 04:02 +0000
Re: Reading beyond the end of file raltbos@xs4all.nl (Richard Bos) - 2015-10-02 13:11 +0000
Re: Reading beyond the end of file supercat@casperkitty.com - 2015-10-02 09:31 -0700
Re: Reading beyond the end of file Richard Damon <Richard@Damon-Family.org> - 2015-10-03 16:07 -0400
Re: Reading beyond the end of file Tim Rentsch <txr@alumni.caltech.edu> - 2015-10-04 19:06 -0700
Re: Reading beyond the end of file Keith Thompson <kst-u@mib.org> - 2015-09-11 14:36 -0700
Re: Reading beyond the end of file Tim Rentsch <txr@alumni.caltech.edu> - 2015-09-26 14:05 -0700
Re: Reading beyond the end of file Keith Thompson <kst-u@mib.org> - 2015-09-26 18:53 -0700
Re: Reading beyond the end of file Tim Rentsch <txr@alumni.caltech.edu> - 2015-10-01 13:49 -0700
Re: Reading beyond the end of file Richard Damon <Richard@Damon-Family.org> - 2015-10-01 20:23 -0400
Re: Reading beyond the end of file glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2015-10-02 06:14 +0000
Re: Reading beyond the end of file Tim Rentsch <txr@alumni.caltech.edu> - 2015-10-04 19:03 -0700
Re: Reading beyond the end of file Richard Damon <Richard@Damon-Family.org> - 2015-10-04 22:55 -0400
Re: Reading beyond the end of file glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2015-10-05 04:27 +0000
Re: Reading beyond the end of file Keith Thompson <kst-u@mib.org> - 2015-10-04 22:21 -0700
Re: Reading beyond the end of file glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2015-10-05 09:53 +0000
Re: Reading beyond the end of file James Kuyper <jameskuyper@verizon.net> - 2015-10-05 13:15 -0400
Re: Reading beyond the end of file supercat@casperkitty.com - 2015-10-05 10:25 -0700
Re: Reading beyond the end of file glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2015-10-05 21:30 +0000
Re: Reading beyond the end of file glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2015-10-05 21:27 +0000
Re: Reading beyond the end of file supercat@casperkitty.com - 2015-10-05 10:17 -0700
Re: Reading beyond the end of file Keith Thompson <kst-u@mib.org> - 2015-10-05 11:59 -0700
Re: Reading beyond the end of file supercat@casperkitty.com - 2015-10-05 13:44 -0700
Re: Reading beyond the end of file glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2015-10-05 21:58 +0000
Ones' complement subtraction supercat@casperkitty.com - 2015-10-05 15:28 -0700
Re: Ones' complement subtraction glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2015-10-06 02:14 +0000
Re: Ones' complement subtraction supercat@casperkitty.com - 2015-10-06 08:48 -0700
Re: Ones' complement subtraction glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2015-10-06 20:55 +0000
Re: Ones' complement subtraction supercat@casperkitty.com - 2015-10-06 14:41 -0700
Re: Ones' complement subtraction glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2015-10-07 00:14 +0000
Re: Reading beyond the end of file Keith Thompson <kst-u@mib.org> - 2015-10-05 15:24 -0700
Re: Reading beyond the end of file glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2015-10-05 21:39 +0000
Re: Reading beyond the end of file Keith Thompson <kst-u@mib.org> - 2015-10-05 15:31 -0700
Re: Reading beyond the end of file glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2015-10-06 03:04 +0000
Re: Reading beyond the end of file Keith Thompson <kst-u@mib.org> - 2015-10-06 08:55 -0700
Re: Reading beyond the end of file supercat@casperkitty.com - 2015-10-06 11:44 -0700
Re: Reading beyond the end of file Richard Damon <Richard@Damon-Family.org> - 2015-10-05 23:16 -0400
Re: Reading beyond the end of file James Kuyper <jameskuyper@verizon.net> - 2015-10-06 10:29 -0400
Re: Reading beyond the end of file Keith Thompson <kst-u@mib.org> - 2015-10-06 08:56 -0700
Re: Reading beyond the end of file Richard Damon <Richard@Damon-Family.org> - 2015-10-06 23:13 -0400
Re: Reading beyond the end of file supercat@casperkitty.com - 2015-10-06 22:01 -0700
Re: Reading beyond the end of file Keith Thompson <kst-u@mib.org> - 2015-10-07 08:43 -0700
Re: Reading beyond the end of file supercat@casperkitty.com - 2015-10-07 10:02 -0700
Re: Reading beyond the end of file Keith Thompson <kst-u@mib.org> - 2015-10-07 13:08 -0700
Re: Reading beyond the end of file Richard Damon <Richard@Damon-Family.org> - 2015-10-07 22:03 -0400
Re: Reading beyond the end of file Tim Rentsch <txr@alumni.caltech.edu> - 2015-10-05 01:47 -0700
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