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| Newsgroups | comp.lang.c |
|---|---|
| Date | 2015-11-24 02:46 -0800 |
| References | <dc62f43a-1725-496b-b36a-c3e196015b7d@googlegroups.com> |
| Message-ID | <f786cecb-e476-4d9a-a4ee-e6b95aca17ba@googlegroups.com> (permalink) |
| Subject | Re: Issue on assigning address to pointers |
| From | guinness.tony@gmail.com |
On Tuesday, 17 November 2015 16:49:38 UTC, Alla _ wrote:
<snip>
> Please, take a look at a paragraph from K&R, stating that this method
> doesn't work on "multi-tasking machines". Given K&R was published in
> 1999, I wonder if that statement still holds.
>
> QUOTE:
> char arrayname[5];
> char *ptr;
> for (ptr = arrayname; ptr <= arrayname+4; ptr++)
> {
> *ptr = 0;
> }
> The code above sets the array arrayname to zero. This method of getting
> at array data is not recommended by this author except in very simple
> computer environments. If a program is running on a normal microcomputer,
> then there should be few problems with this alternative method of handling
> arrays. On the hand, if the microcomputer is multi-tasking, or the program
> is running on a larger system which has a limited manager, then memory
> ceases to be something which can be thought of as a sequence of boxes
> standing next to one another. A multi-tasking system shares memory with
> Questions 175
> other programs and it takes what it can find, where it can find it. The upshot
> of this is that it is not possible to guarantee that arrays will be stored in one
> simple string of memory locations: it might be scattered around in different
> places. So
> ptr = arrayname + 5;
> might not be a pointer to the fifth character in a character array. This could
> be found instead using the '&' operator. A pointer to the fifth element can
> be reliably found with:
> ptr = &(arrayname[5]);
> Be warned!
> END OF QUOTE
Surely that doesn't appear in K&R? (I don't have a copy to hand).
Both Brian and Dennis were good writers - I doubt that they (nor their
publisher's proof-readers) would have allowed the phrase "on the hand"
to have slipped through into the final publication. Nor would they have
made the glaring error of referring to 'arrayname + 5' and '&(arrayname[5])'
as 'the fifth character' and 'the fifth element'. And they are plural -
the phrase "this author" would not appear in any joint work of theirs.
That quoted text appears to come from this document:
http://markburgess.org/CTutorial/C-Tut-4.02.pdf
rather than from K&R.
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Issue on assigning address to pointers Alla _ <modelling.data@gmail.com> - 2015-11-17 08:49 -0800
Re: Issue on assigning address to pointers James Kuyper <jameskuyper@verizon.net> - 2015-11-17 12:36 -0500
Re: Issue on assigning address to pointers Richard Heathfield <rjh@cpax.org.uk> - 2015-11-17 17:47 +0000
Re: Issue on assigning address to pointers Alla _ <modelling.data@gmail.com> - 2015-11-17 10:34 -0800
Re: Issue on assigning address to pointers Keith Thompson <kst-u@mib.org> - 2015-11-17 12:16 -0800
Re: Issue on assigning address to pointers James Kuyper <jameskuyper@verizon.net> - 2015-11-17 15:23 -0500
Re: Issue on assigning address to pointers Alla _ <modelling.data@gmail.com> - 2015-11-17 10:33 -0800
Re: Issue on assigning address to pointers Keith Thompson <kst-u@mib.org> - 2015-11-17 09:41 -0800
Re: Issue on assigning address to pointers Geoff <geoff@invalid.invalid> - 2015-11-17 10:03 -0800
Re: Issue on assigning address to pointers glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2015-11-17 20:31 +0000
Re: Issue on assigning address to pointers Geoff <geoff@invalid.invalid> - 2015-11-17 12:53 -0800
Re: Issue on assigning address to pointers Alla _ <modelling.data@gmail.com> - 2015-11-17 10:32 -0800
Re: Issue on assigning address to pointers Richard Heathfield <rjh@cpax.org.uk> - 2015-11-17 18:45 +0000
Re: Issue on assigning address to pointers Alla _ <modelling.data@gmail.com> - 2015-11-17 10:53 -0800
Re: Issue on assigning address to pointers Keith Thompson <kst-u@mib.org> - 2015-11-17 15:05 -0800
Re: Issue on assigning address to pointers Philip Lantz <prl@canterey.us> - 2015-11-19 21:16 -0800
Re: Issue on assigning address to pointers Anand Hariharan <mailto.anand.hariharan@gmail.com> - 2015-11-17 15:47 -0800
Re: Issue on assigning address to pointers Barry Schwarz <schwarzb@dqel.com> - 2015-11-17 15:53 -0800
Re: Issue on assigning address to pointers Richard Heathfield <rjh@cpax.org.uk> - 2015-11-18 04:05 +0000
Re: Issue on assigning address to pointers Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-11-17 19:41 +0000
Re: Issue on assigning address to pointers Stephen Sprunk <stephen@sprunk.org> - 2015-11-17 12:17 -0600
Re: Issue on assigning address to pointers Richard Heathfield <rjh@cpax.org.uk> - 2015-11-17 18:21 +0000
Re: Issue on assigning address to pointers Geoff <geoff@invalid.invalid> - 2015-11-17 10:36 -0800
Re: Issue on assigning address to pointers Richard Heathfield <rjh@cpax.org.uk> - 2015-11-17 18:46 +0000
Re: Issue on assigning address to pointers Alla _ <modelling.data@gmail.com> - 2015-11-17 10:49 -0800
Re: Issue on assigning address to pointers Alla _ <modelling.data@gmail.com> - 2015-11-17 10:47 -0800
Re: Issue on assigning address to pointers Richard Heathfield <rjh@cpax.org.uk> - 2015-11-17 18:51 +0000
Re: Issue on assigning address to pointers Alla _ <modelling.data@gmail.com> - 2015-11-17 10:55 -0800
Re: Issue on assigning address to pointers Geoff <geoff@invalid.invalid> - 2015-11-17 11:59 -0800
Re: Issue on assigning address to pointers Stephen Sprunk <stephen@sprunk.org> - 2015-11-17 12:58 -0600
Re: Issue on assigning address to pointers Richard Heathfield <rjh@cpax.org.uk> - 2015-11-17 19:12 +0000
Re: Issue on assigning address to pointers Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-11-17 19:33 +0000
Re: Issue on assigning address to pointers Lew Pitcher <lew.pitcher@digitalfreehold.ca> - 2015-11-17 13:25 -0500
Re: Issue on assigning address to pointers Richard Heathfield <rjh@cpax.org.uk> - 2015-11-17 18:31 +0000
Re: Issue on assigning address to pointers Alla _ <modelling.data@gmail.com> - 2015-11-17 10:39 -0800
Re: Issue on assigning address to pointers Alla _ <modelling.data@gmail.com> - 2015-11-17 10:40 -0800
Re: Issue on assigning address to pointers Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-11-17 19:40 +0000
Re: Issue on assigning address to pointers Geoff <geoff@invalid.invalid> - 2015-11-17 11:15 -0800
Re: Issue on assigning address to pointers James Kuyper <jameskuyper@verizon.net> - 2015-11-17 15:32 -0500
Re: Issue on assigning address to pointers Keith Thompson <kst-u@mib.org> - 2015-11-17 15:09 -0800
Re: Issue on assigning address to pointers supercat@casperkitty.com - 2015-11-17 15:41 -0800
Re: Issue on assigning address to pointers Malcolm McLean <malcolm.mclean5@btinternet.com> - 2015-11-17 21:28 -0800
Re: Issue on assigning address to pointers supercat@casperkitty.com - 2015-11-17 23:18 -0800
Re: Issue on assigning address to pointers Geoff <geoff@invalid.invalid> - 2015-11-17 17:18 -0800
Re: Issue on assigning address to pointers James Kuyper <jameskuyper@verizon.net> - 2015-11-17 22:37 -0500
Re: Issue on assigning address to pointers Lőrinczy Zsigmond <zsiga@nospam.for.me> - 2015-11-18 11:27 +0100
Re: Issue on assigning address to pointers Keith Thompson <kst-u@mib.org> - 2015-11-18 06:13 -0800
Re: Issue on assigning address to pointers guinness.tony@gmail.com - 2015-11-24 02:46 -0800
Re: Issue on assigning address to pointers Keith Thompson <kst-u@mib.org> - 2015-11-24 09:21 -0800
Re: Issue on assigning address to pointers John Bode <jfbode1029@gmail.com> - 2015-11-24 05:01 -0800
Re: Issue on assigning address to pointers Keith Thompson <kst-u@mib.org> - 2015-11-24 09:22 -0800
Re: Issue on assigning address to pointers John Bode <jfbode1029@gmail.com> - 2015-11-24 06:47 -0800
Re: Issue on assigning address to pointers Alla _ <modelling.data@gmail.com> - 2015-11-25 06:44 -0800
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