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| From | Tim Rentsch <txr@alumni.caltech.edu> |
|---|---|
| Newsgroups | comp.lang.c |
| Subject | Re: the language |
| Date | 2014-11-28 12:53 -0800 |
| Organization | A noiseless patient Spider |
| Message-ID | <kfnk32ft5ce.fsf@x-alumni2.alumni.caltech.edu> (permalink) |
| References | (1 earlier) <kpBdw.5607$n97.3994@fx05.am4> <m56o8r$g27$1@dont-email.me> <m57gcm$20f$2@news.xmission.com> <YKIdw.878897$yK.495811@fx14.iad> <cdpnqnFr5qjU2@mid.uni-berlin.de> |
jt@toerring.de (Jens Thoms Toerring) writes: > Richard Damon <Richard@damon-family.org> wrote: >> It strictly isn't portability that cause some things to be >> undefined, but the desire to make valid code run as fast as >> possible. I believe that virtually all of the "undefined behavior" >> in C could be defined at the cost of a lot of run-time checking and >> enforcing defined results. (Pointers would need to become "fat" to >> hold/point to bounds checking info). What can't be checked at run >> time should be able to be checked at (post) compile time to find >> all the undefined behavior caused by mis-matches between >> translation units. > > What about stuff also not uncommon to be done in C (or, more > precisely, very often is done in C), i.e. controlling hardware? > If a certain device is for example memory-mapped (i.e. to com- > municate with the device one has to write data to that memory > location or read from it), then one needs to be able to access > that address without C keeping you from doing that. According > to the standard this invokes "undefined behaviour" - you are > going to use a pointer to something you didn't allocate. [snip] I disagree. There is nothing in the Standard that says no other objects exist. The semantics of '*' requires only that the pointer designate an object, not one allocated by the program. Obtaining such a pointer most likely depends on implementation-defined behavior (eg, by converting an integer), but as long as that pointer refers to "a region of data storage in the execution environment, the contents of which can represent values", the behavior is defined, not undefined (assuming of course alignment requirements are satisfied, appropriate qualifier restrictions are observed, etc). Nothing prevents an implementation from designating a specific memory location as such a region; the behavior in such cases can be implementation specific, but it is not ipso facto undefined.
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the language Rosario193 <Rosario@invalid.invalid> - 2014-11-26 21:54 +0100
Re: the language Rosario193 <Rosario@invalid.invalid> - 2014-11-26 21:56 +0100
Re: the language John Bode <jfbode1029@gmail.com> - 2014-11-26 13:45 -0800
Re: the language Rosario193 <Rosario@invalid.invalid> - 2014-11-28 11:52 +0100
Re: the language "Bill Cunningham" <nospam@nspam.invalid> - 2014-12-01 23:25 -0500
Re: the language "Bill Cunningham" <nospam@nspam.invalid> - 2014-12-02 00:56 -0500
Re: the language Rosario193 <Rosario@invalid.invalid> - 2014-12-04 14:52 +0100
Re: the language "Osmium" <r124c4u102@comcast.net> - 2014-12-04 08:07 -0600
Re: the language Geoff <geoff@invalid.invalid> - 2014-12-04 10:20 -0800
Re: the language Mark Storkamp <mstorkamp@yahoo.com> - 2014-11-26 15:11 -0600
Re: the language Rosario193 <Rosario@invalid.invalid> - 2014-11-28 12:16 +0100
Re: the language Rosario193 <Rosario@invalid.invalid> - 2014-11-28 12:18 +0100
Re: the language John Bode <jfbode1029@gmail.com> - 2014-11-26 13:12 -0800
Re: the language Kaz Kylheku <kaz@kylheku.com> - 2014-11-27 00:37 +0000
Re: the language Ben Bacarisse <ben.usenet@bsb.me.uk> - 2014-11-27 01:13 +0000
Re: the language raltbos@xs4all.nl (Richard Bos) - 2014-11-26 22:45 +0000
Re: the language Rosario193 <Rosario@invalid.invalid> - 2014-11-27 07:41 +0100
Re: the language Rosario193 <Rosario@invalid.invalid> - 2014-11-27 08:12 +0100
Re: the language Morris Dovey <mrdovey@iedu.com> - 2014-11-27 01:43 -0600
Re: the language Rosario193 <Rosario@invalid.invalid> - 2014-11-28 11:56 +0100
Re: the language Morris Dovey <mrdovey@iedu.com> - 2014-11-28 09:08 -0600
Re: the language Rosario193 <Rosario@invalid.invalid> - 2014-11-28 20:58 +0100
Re: the language Morris Dovey <mrdovey@iedu.com> - 2014-11-28 19:22 -0600
Re: the language Rosario193 <Rosario@invalid.invalid> - 2014-12-02 02:59 +0100
Re: the language Kaz Kylheku <kaz@kylheku.com> - 2014-12-02 02:53 +0000
Re: the language Les Cargill <lcargill99@comcast.com> - 2014-12-01 21:25 -0600
Re: the language Kaz Kylheku <kaz@kylheku.com> - 2014-12-02 06:22 +0000
Re: the language Richard Heathfield <invalid@see.sig.invalid> - 2014-11-27 08:37 +0000
Re: the language Reinhardt Behm <rbehm@hushmail.com> - 2014-11-27 16:44 +0800
Re: the language gazelle@shell.xmission.com (Kenny McCormack) - 2014-11-27 15:35 +0000
Re: the language Richard Damon <Richard@Damon-Family.org> - 2014-11-27 11:58 -0500
Re: the language jt@toerring.de (Jens Thoms Toerring) - 2014-11-27 22:44 +0000
Re: the language Rosario193 <Rosario@invalid.invalid> - 2014-11-28 09:52 +0100
Re: the language Tim Rentsch <txr@alumni.caltech.edu> - 2014-11-28 12:53 -0800
Re: the language Thomas Jahns <jahns@idontlikespam.dkrz.de> - 2014-11-28 10:07 +0100
Re: the language Thomas Jahns <jahns@idontlikespam.dkrz.de> - 2014-11-28 14:57 +0100
Re: the language Tim Rentsch <txr@alumni.caltech.edu> - 2014-11-28 13:09 -0800
Re: the language Rosario193 <Rosario@invalid.invalid> - 2014-11-28 12:01 +0100
Re: the language Richard Heathfield <invalid@see.sig.invalid> - 2014-11-28 14:46 +0000
Re: the language Tim Rentsch <txr@alumni.caltech.edu> - 2014-11-28 13:16 -0800
Re: the language gazelle@shell.xmission.com (Kenny McCormack) - 2014-11-28 22:09 +0000
Re: the language Tim Rentsch <txr@alumni.caltech.edu> - 2014-12-01 03:40 -0800
Re: the language Malcolm McLean <malcolm.mclean5@btinternet.com> - 2014-11-28 14:42 -0800
Re: the language Tim Rentsch <txr@alumni.caltech.edu> - 2014-12-01 03:22 -0800
Re: the language Richard Heathfield <invalid@see.sig.invalid> - 2014-11-28 23:09 +0000
Re: the language Malcolm McLean <malcolm.mclean5@btinternet.com> - 2014-11-28 16:14 -0800
Re: the language BartC <bc@freeuk.com> - 2014-11-29 01:42 +0000
Re: the language Kaz Kylheku <kaz@kylheku.com> - 2014-11-29 01:42 +0000
Re: the language Malcolm McLean <malcolm.mclean5@btinternet.com> - 2014-11-29 04:03 -0800
Re: the language Keith Thompson <kst-u@mib.org> - 2014-12-01 00:55 -0800
Re: the language glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2014-12-02 05:42 +0000
Re: the language Richard Damon <Richard@Damon-Family.org> - 2014-11-28 19:25 -0500
Re: the language Tim Rentsch <txr@alumni.caltech.edu> - 2014-12-01 03:21 -0800
Re: the language Richard Heathfield <invalid@see.sig.invalid> - 2014-12-01 14:02 +0000
Re: the language Tim Rentsch <txr@alumni.caltech.edu> - 2014-12-05 10:18 -0800
Re: the language Richard Heathfield <invalid@see.sig.invalid> - 2014-12-07 08:25 +0000
Re: the language Öö Tiib <ootiib@hot.ee> - 2014-12-07 10:44 -0800
Re: the language Richard Heathfield <invalid@see.sig.invalid> - 2014-12-07 19:17 +0000
Re: the language Öö Tiib <ootiib@hot.ee> - 2014-12-07 15:48 -0800
Re: the language Richard Heathfield <invalid@see.sig.invalid> - 2014-12-08 05:45 +0000
Re: the language Malcolm McLean <malcolm.mclean5@btinternet.com> - 2014-12-08 03:27 -0800
Re: the language Kaz Kylheku <kaz@kylheku.com> - 2014-12-08 06:00 +0000
Re: the language Richard Heathfield <invalid@see.sig.invalid> - 2014-12-08 06:17 +0000
Re: the language Malcolm McLean <malcolm.mclean5@btinternet.com> - 2014-12-08 03:37 -0800
Re: the language Richard Heathfield <invalid@see.sig.invalid> - 2014-12-08 12:53 +0000
Re: the language Tim Rentsch <txr@alumni.caltech.edu> - 2014-12-16 04:21 -0800
Re: the language Richard Heathfield <invalid@see.sig.invalid> - 2014-12-16 12:43 +0000
Re: the language Tim Rentsch <txr@alumni.caltech.edu> - 2014-12-16 14:46 -0800
Re: the language Richard Heathfield <invalid@see.sig.invalid> - 2014-12-17 00:23 +0000
Re: the language JohnF <john@please.see.sig.for.email.com> - 2014-12-17 07:01 +0000
Re: the language Richard Heathfield <invalid@see.sig.invalid> - 2014-12-17 07:22 +0000
Re: the language Ben Bacarisse <ben.usenet@bsb.me.uk> - 2014-12-17 11:56 +0000
Re: the language Malcolm McLean <malcolm.mclean5@btinternet.com> - 2014-12-17 05:43 -0800
Re: the language Rosario193 <Rosario@invalid.invalid> - 2014-12-18 18:30 +0100
Re: the language Rosario193 <Rosario@invalid.invalid> - 2014-12-18 18:41 +0100
Re: the language Richard Heathfield <invalid@see.sig.invalid> - 2014-12-17 14:34 +0000
Re: the language Ben Bacarisse <ben.usenet@bsb.me.uk> - 2014-12-18 02:15 +0000
Re: the language James Kuyper <jameskuyper@verizon.net> - 2014-12-17 22:31 -0500
Re: the language Ben Bacarisse <ben.usenet@bsb.me.uk> - 2014-12-18 17:19 +0000
Re: the language Richard Heathfield <invalid@see.sig.invalid> - 2014-12-18 07:52 +0000
Re: the language Ben Bacarisse <ben.usenet@bsb.me.uk> - 2014-12-18 17:21 +0000
Re: the language Richard Heathfield <invalid@see.sig.invalid> - 2014-12-18 18:15 +0000
Re: the language Ben Bacarisse <ben.usenet@bsb.me.uk> - 2014-12-19 01:20 +0000
Re: the language Richard Heathfield <invalid@see.sig.invalid> - 2014-12-19 07:48 +0000
Re: the language James Kuyper <jameskuyper@verizon.net> - 2014-12-19 07:40 -0500
Re: the language Richard Heathfield <invalid@see.sig.invalid> - 2014-12-19 12:54 +0000
Re: the language James Kuyper <jameskuyper@verizon.net> - 2014-12-19 09:54 -0500
Re: the language Richard Heathfield <invalid@see.sig.invalid> - 2014-12-19 15:19 +0000
Re: the language James Kuyper <jameskuyper@verizon.net> - 2014-12-19 11:00 -0500
Re: the language Richard Heathfield <invalid@see.sig.invalid> - 2014-12-19 16:13 +0000
Re: the language James Kuyper <jameskuyper@verizon.net> - 2014-12-19 11:27 -0500
Re: the language Richard Heathfield <invalid@see.sig.invalid> - 2014-12-19 16:45 +0000
Re: the language James Kuyper <jameskuyper@verizon.net> - 2014-12-19 13:48 -0500
Re: the language Richard Heathfield <invalid@see.sig.invalid> - 2014-12-19 19:10 +0000
Re: the language Morris Dovey <mrdovey@iedu.com> - 2014-12-19 21:17 -0600
Re: the language Morris Dovey <mrdovey@iedu.com> - 2014-12-19 21:32 -0600
Re: the language Ben Bacarisse <ben.usenet@bsb.me.uk> - 2014-12-19 16:49 +0000
Re: the language Richard Heathfield <invalid@see.sig.invalid> - 2014-12-19 17:00 +0000
Re: the language James Kuyper <jameskuyper@verizon.net> - 2014-12-19 13:57 -0500
Re: the language Malcolm McLean <malcolm.mclean5@btinternet.com> - 2014-12-19 14:31 -0800
Re: the language Ben Bacarisse <ben.usenet@bsb.me.uk> - 2014-12-19 20:29 +0000
Re: the language Richard Heathfield <invalid@see.sig.invalid> - 2014-12-19 20:36 +0000
Re: the language Tim Rentsch <txr@alumni.caltech.edu> - 2014-12-17 07:18 -0800
Re: the language Richard Heathfield <invalid@see.sig.invalid> - 2014-12-17 15:45 +0000
Re: the language glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2014-12-17 16:50 +0000
Re: the language raltbos@xs4all.nl (Richard Bos) - 2014-12-17 17:24 +0000
Re: the language Robert Wessel <robertwessel2@yahoo.com> - 2014-12-18 02:07 -0600
Re: the language raltbos@xs4all.nl (Richard Bos) - 2014-12-18 12:04 +0000
Re: the language Richard Damon <Richard@Damon-Family.org> - 2014-12-18 08:06 -0500
Re: the language James Kuyper <jameskuyper@verizon.net> - 2014-12-18 08:30 -0500
Re: the language Richard Damon <Richard@Damon-Family.org> - 2014-12-19 00:11 -0500
Re: the language glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2014-12-19 07:00 +0000
Re: the language Keith Thompson <kst-u@mib.org> - 2014-12-19 08:43 -0800
Re: the language Richard Damon <Richard@Damon-Family.org> - 2014-12-19 23:29 -0500
Re: the language Keith Thompson <kst-u@mib.org> - 2014-12-20 00:37 -0800
Re: the language gazelle@shell.xmission.com (Kenny McCormack) - 2014-12-20 08:45 +0000
Re: the language raltbos@xs4all.nl (Richard Bos) - 2014-12-20 09:45 +0000
Re: the language Malcolm McLean <malcolm.mclean5@btinternet.com> - 2014-12-20 03:17 -0800
Re: the language Malcolm McLean <malcolm.mclean5@btinternet.com> - 2014-12-18 06:09 -0800
Re: the language raltbos@xs4all.nl (Richard Bos) - 2014-12-18 14:30 +0000
Re: the language raltbos@xs4all.nl (Richard Bos) - 2014-12-18 14:23 +0000
Re: the language Keith Thompson <kst-u@mib.org> - 2014-12-18 08:18 -0800
Re: the language Richard Damon <Richard@Damon-Family.org> - 2014-12-20 12:22 -0500
Re: the language James Kuyper <jameskuyper@verizon.net> - 2014-12-20 13:36 -0500
Re: the language Keith Thompson <kst-u@mib.org> - 2014-12-20 11:43 -0800
Re: the language Keith Thompson <kst-u@mib.org> - 2014-12-20 11:37 -0800
Re: the language glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2014-12-20 20:10 +0000
Re: the language Robert Wessel <robertwessel2@yahoo.com> - 2014-12-21 15:02 -0600
Re: the language Kaz Kylheku <kaz@kylheku.com> - 2014-12-21 22:02 +0000
Re: the language Stephen Sprunk <stephen@sprunk.org> - 2014-12-21 23:49 -0600
Re: the language raltbos@xs4all.nl (Richard Bos) - 2014-12-21 17:45 +0000
Re: the language Tim Rentsch <txr@alumni.caltech.edu> - 2014-12-18 10:29 -0800
Re: the language Robert Wessel <robertwessel2@yahoo.com> - 2014-12-20 05:29 -0600
Re: the language Tim Rentsch <txr@alumni.caltech.edu> - 2014-12-20 11:32 -0800
Re: the language Robert Wessel <robertwessel2@yahoo.com> - 2014-12-21 15:23 -0600
Re: the language Tim Rentsch <txr@alumni.caltech.edu> - 2014-12-22 23:39 -0800
Re: the language glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2014-12-20 20:22 +0000
Re: the language Tim Rentsch <txr@alumni.caltech.edu> - 2014-12-18 10:24 -0800
Re: the language Richard Heathfield <invalid@see.sig.invalid> - 2014-12-18 18:36 +0000
Re: the language Tim Rentsch <txr@alumni.caltech.edu> - 2014-12-19 09:24 -0800
Re: the language Richard Heathfield <invalid@see.sig.invalid> - 2014-12-19 17:53 +0000
Re: the language Tim Rentsch <txr@alumni.caltech.edu> - 2014-12-20 11:48 -0800
Re: the language JohnF <john@please.see.sig.for.email.com> - 2014-12-19 02:20 +0000
Re: the language Richard Heathfield <invalid@see.sig.invalid> - 2014-12-19 08:31 +0000
Re: the language JohnF <john@please.see.sig.for.email.com> - 2014-12-19 09:31 +0000
Re: the language Richard Heathfield <invalid@see.sig.invalid> - 2014-12-19 10:10 +0000
Re: the language Malcolm McLean <malcolm.mclean5@btinternet.com> - 2014-12-19 07:08 -0800
Re: the language JohnF <john@please.see.sig.for.email.com> - 2014-12-20 06:39 +0000
Re: the language John Forkosh <forkosh@panix.com> - 2014-12-20 07:32 +0000
Re: the language Greg Martin <greg.at.softsprocket@dot.com> - 2015-01-04 17:02 +0000
Re: the language James Kuyper <jameskuyper@verizon.net> - 2015-01-04 12:40 -0500
Re: the language Greg Martin <greg.at.softsprocket@dot.com> - 2015-01-04 18:02 +0000
Re: the language James Kuyper <jameskuyper@verizon.net> - 2015-01-05 09:47 -0500
Re: the language Greg Martin <greg.at.softsprocket@dot.com> - 2015-01-05 15:14 +0000
Re: the language Keith Thompson <kst-u@mib.org> - 2015-01-05 08:42 -0800
Re: the language glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2015-01-06 00:14 +0000
Re: the language James Kuyper <jameskuyper@verizon.net> - 2015-01-05 13:19 -0500
Re: the language Richard Damon <Richard@Damon-Family.org> - 2015-01-04 15:59 -0500
Re: the language Keith Thompson <kst-u@mib.org> - 2015-01-04 14:30 -0800
Re: the language Malcolm McLean <malcolm.mclean5@btinternet.com> - 2015-01-04 15:44 -0800
Re: the language James Kuyper <jameskuyper@verizon.net> - 2015-01-05 13:36 -0500
Re: the language Rosario193 <Rosario@invalid.invalid> - 2014-11-28 12:07 +0100
Re: the language "ocq (an evil corporate man)" <ocq@maili.ng> - 2014-12-02 23:16 +0100
Re: the language Malcolm McLean <malcolm.mclean5@btinternet.com> - 2014-12-03 02:23 -0800
Re: the language "ocq (an evil corporate man)" <ocq@maili.ng> - 2014-12-03 15:55 +0100
Re: the language Nobody <nobody@nowhere.invalid> - 2014-12-03 15:42 +0000
Re: the language Malcolm McLean <malcolm.mclean5@btinternet.com> - 2014-12-04 04:49 -0800
Re: the language Keith Thompson <kst-u@mib.org> - 2014-12-04 09:07 -0800
Re: the language Malcolm McLean <malcolm.mclean5@btinternet.com> - 2014-12-04 10:08 -0800
Re: the language Keith Thompson <kst-u@mib.org> - 2014-12-04 11:49 -0800
Re: the language Rosario193 <Rosario@invalid.invalid> - 2014-12-05 12:32 +0100
Re: the language raltbos@xs4all.nl (Richard Bos) - 2014-12-04 22:17 +0000
Re: the language Rosario193 <Rosario@invalid.invalid> - 2014-12-18 18:17 +0100
Re: the language Richard Heathfield <invalid@see.sig.invalid> - 2014-12-18 18:12 +0000
Re: the language Rosario193 <Rosario@invalid.invalid> - 2014-12-18 23:15 +0100
Re: the language Rosario193 <Rosario@invalid.invalid> - 2014-12-18 23:50 +0100
Re: the language "ocq (an evil corporate man)" <ocq@maili.ng> - 2014-12-19 02:34 +0100
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