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| From | John Gordon <gordon@panix.com> |
|---|---|
| Newsgroups | comp.lang.c |
| Subject | Re: int * vs char * |
| Date | 2011-06-21 21:58 +0000 |
| Organization | PANIX Public Access Internet and UNIX, NYC |
| Message-ID | <itr46q$243$1@reader1.panix.com> (permalink) |
| References | <itr3lm$i8j$1@speranza.aioe.org> |
In <itr3lm$i8j$1@speranza.aioe.org> yugandhar <nospam@nospam.com> writes:
> Hi Forum,
> I have a quick question.
> The following works:
> char *s="hello";
> *s="world";
It shouldn't work. A character pointer declared in that way should be
non-writable. It's an accident that it "worked" (did the wrong thing)
for you.
> but the following gives a segementation fault:
> int *p = 0;
> *p = 17;
> Could anyone please clarify me about this?
Setting a pointer equal to zero is a special case.
Zero is another way of saying NULL. So when you declare a pointer that
is equal to zero, it's really a NULL pointer. It doesn't point anywhere.
So, when you say "Insert 17 at the location pointed to by this pointer",
it has no place to put the value 17, since you told it to point nowhere.
--
John Gordon A is for Amy, who fell down the stairs
gordon@panix.com B is for Basil, assaulted by bears
-- Edward Gorey, "The Gashlycrumb Tinies"
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int * vs char * yugandhar <nospam@nospam.com> - 2011-06-21 21:49 +0000
Re: int * vs char * John Gordon <gordon@panix.com> - 2011-06-21 21:58 +0000
Re: int * vs char * "Morris Keesan" <mkeesan@post.harvard.edu> - 2011-06-21 20:25 -0400
Re: int * vs char * Ian Collins <ian-news@hotmail.com> - 2011-06-22 09:59 +1200
Re: int * vs char * Ike Naar <ike@sverige.freeshell.org> - 2011-06-21 22:18 +0000
Re: int * vs char * Shao Miller <sha0.miller@gmail.com> - 2011-06-21 18:34 -0500
Re: int * vs char * Keith Thompson <kst-u@mib.org> - 2011-06-21 15:42 -0700
Re: int * vs char * Noob <root@127.0.0.1> - 2011-06-22 10:28 +0200
Re: int * vs char * Shao Miller <sha0.miller@gmail.com> - 2011-06-22 05:23 -0500
Re: int * vs char * James Kuyper <jameskuyper@verizon.net> - 2011-06-22 06:25 -0400
Re: int * vs char * Ian Collins <ian-news@hotmail.com> - 2011-06-23 07:56 +1200
Re: int * vs char * Shao Miller <sha0.miller@gmail.com> - 2011-06-22 18:12 -0500
Re: int * vs char * Ian Collins <ian-news@hotmail.com> - 2011-06-23 10:23 +1200
Re: int * vs char * Keith Thompson <kst-u@mib.org> - 2011-06-22 17:23 -0700
Re: int * vs char * Ian Collins <ian-news@hotmail.com> - 2011-06-23 12:54 +1200
Re: int * vs char * Keith Thompson <kst-u@mib.org> - 2011-06-22 18:18 -0700
Re: int * vs char * Ian Collins <ian-news@hotmail.com> - 2011-06-23 13:23 +1200
Re: int * vs char * Shao Miller <sha0.miller@gmail.com> - 2011-06-24 15:39 -0400
Re: int * vs char * Ian Collins <ian-news@hotmail.com> - 2011-06-25 09:28 +1200
Re: int * vs char * Keith Thompson <kst-u@mib.org> - 2011-06-24 14:58 -0700
Re: int * vs char * Ian Collins <ian-news@hotmail.com> - 2011-06-25 10:06 +1200
Re: int * vs char * Shao Miller <sha0.miller@gmail.com> - 2011-06-26 15:44 -0500
Re: int * vs char * Keith Thompson <kst-u@mib.org> - 2011-06-24 14:29 -0700
Re: int * vs char * Ian Collins <ian-news@hotmail.com> - 2011-06-25 09:36 +1200
Re: int * vs char * Shao Miller <sha0.miller@gmail.com> - 2011-06-26 16:24 -0500
Re: int * vs char * Tim Rentsch <txr@alumni.caltech.edu> - 2011-06-25 08:39 -0700
Re: int * vs char * gordonb.5qick@burditt.org (Gordon Burditt) - 2011-06-22 23:49 -0500
Re: int * vs char * Stephen Sprunk <stephen@sprunk.org> - 2011-06-22 11:31 -0500
Re: int * vs char * gordonb.idn9q@burditt.org (Gordon Burditt) - 2011-06-23 00:45 -0500
Re: int * vs char * pacman@kosh.dhis.org (Alan Curry) - 2011-06-23 20:08 +0000
Re: int * vs char * Stephen Sprunk <stephen@sprunk.org> - 2011-06-23 22:40 -0500
Re: int * vs char * Ian Collins <ian-news@hotmail.com> - 2011-06-24 15:46 +1200
Re: int * vs char * Stephen Sprunk <stephen@sprunk.org> - 2011-06-24 09:24 -0500
Re: int * vs char * Shao Miller <sha0.miller@gmail.com> - 2011-07-04 18:00 -0400
Re: int * vs char * Dr Nick <3-nospam@temporary-address.org.uk> - 2011-07-05 07:45 +0100
Re: int * vs char * Harald van Dijk <truedfx@gmail.com> - 2011-07-05 10:39 -0700
Re: int * vs char * Shao Miller <sha0.miller@gmail.com> - 2011-07-05 14:09 -0400
Re: int * vs char * Phil Carmody <thefatphil_demunged@yahoo.co.uk> - 2011-07-07 21:56 +0300
Re: int * vs char * Phil Carmody <thefatphil_demunged@yahoo.co.uk> - 2011-07-08 02:46 +0300
Re: int * vs char * Shao Miller <sha0.miller@gmail.com> - 2011-07-07 22:26 -0400
Re: int * vs char * Stephen Sprunk <stephen@sprunk.org> - 2011-07-07 22:41 -0500
Re: int * vs char * "Joel C. Salomon" <joelcsalomon@gmail.com> - 2011-07-05 15:32 -0400
Re: int * vs char * Shao Miller <sha0.miller@gmail.com> - 2011-07-06 09:58 -0400
Re: int * vs char * Tim Rentsch <txr@alumni.caltech.edu> - 2011-06-23 01:02 -0700
Re: int * vs char * Ian Collins <ian-news@hotmail.com> - 2011-06-23 20:11 +1200
Re: int * vs char * Tim Rentsch <txr@alumni.caltech.edu> - 2011-06-25 09:23 -0700
Re: int * vs char * Keith Thompson <kst-u@mib.org> - 2011-06-25 12:37 -0700
Re: int * vs char * Tim Rentsch <txr@alumni.caltech.edu> - 2011-06-27 11:40 -0700
Re: int * vs char * Eric Sosman <esosman@ieee-dot-org.invalid> - 2011-06-21 21:46 -0400
Re: int * vs char * "Kleuskes & Moos" <kleuske@xs4all.nl> - 2011-06-22 10:06 -0700
Re: int * vs char * Keith Thompson <kst-u@mib.org> - 2011-06-22 13:06 -0700
Re: int * vs char * "Kleuskes & Moos" <kleuske@xs4all.nl> - 2011-06-22 13:29 -0700
Re: int * vs char * Stephen Sprunk <stephen@sprunk.org> - 2011-06-21 21:29 -0500
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