X-Authentication-Warning: delorie.com: mail set sender to djgpp-bounces using -f
From: Martin Ambuhl <mambuhl AT earthlink DOT net>
Newsgroups: comp.os.msdos.djgpp
Subject: Re: pointers to structs
Date: Wed, 14 Jul 2004 19:07:15 -0400
Lines: 32
Message-ID: <2llslbFe5t0pU2@uni-berlin.de>
References: <1089842517 DOT 34974 AT proxy2 DOT srv DOT ualberta DOT ca>
Mime-Version: 1.0
Content-Type: text/plain; charset=us-ascii; format=flowed
Content-Transfer-Encoding: 7bit
X-Trace: news.uni-berlin.de 6FPhL7B7v+Tq+ekUSLoSvAheqp1cz7/oMqpov/nYGuCAYNv96k
User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.7) Gecko/20040616
X-Accept-Language: en-us, en, de, fr, ru, zh, ja
In-Reply-To: <1089842517.34974@proxy2.srv.ualberta.ca>
To: djgpp AT delorie DOT com
DJ-Gateway: from newsgroup comp.os.msdos.djgpp
Reply-To: djgpp AT delorie DOT com
Errors-To: nobody AT delorie DOT com
X-Mailing-List: djgpp AT delorie DOT com
X-Unsubscribes-To: listserv AT delorie DOT com
Precedence: bulk

John Hanley wrote:

> I am creating a linked list.  I have 2 structs:
> 
> struct data_record
> {
>     struct data_record * next;
> };
> 
> struct data_list
> {
>     struct data_record * head;
>     struct data_record * tail;
> };
> 
> int main()
> {
>     struct data_list * list;
> 
>     list->head = NULL;
>     list->tail = NULL;
> }
> 
> When I compile then run this, I get:  "Exiting due to Signal SIGSEGV.  Page
> Fault at ..."
> 
> Can I not assign NULL to these pointers? 

There are no pointers, except for 'list', which points nowhere.  'list' 
needs to have storage allocated for it to point to before there are any 
list->head or list->tail to use.