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Groups > comp.lang.c > #22464

Re: dequeue() not working

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On 2012-06-21, arnuld <sunrise@invalid.address> wrote:
> struct myQ* dequeue(struct myList** s)
> {
>   struct myQ *temp, *prev;
>   if(NULL == s || NULL == *s) return 0;
>   if(NULL == (*s)->head) return 0;
>   prev = (*s)->head;
>   temp = (*s)->head;
>   if(NULL == (*s)->head->next)
>     {
>       struct myQ* retp = (*s)->head;
>       (*s)->head = (*s)->tail = NULL;
>       return retp;
>     }
>   
>   while(temp->next)
>     {
>       prev = temp;
>       temp = temp->next;
>     }
>
>   (*s)->tail = prev;

Didn't you forget to set prev->next to NULL here?

>
>   return temp;
> }

The code above could be simplified in a couple of ways.

First, you can change the type of s to struct mylist*
and replace every (*s) by s.
(and of course, change the call dequeue(&s) to dequeue(s)).

Second, the tail pointer in a struct MyList does not add
much value, so you might as well get rid of it. The last
element in a list is already characterized by element->next
being NULL, and it is that property that you use everywhere.

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Thread

dequeue() not working arnuld <sunrise@invalid.address> - 2012-06-21 07:11 +0000
  Re: dequeue() not working Ike Naar <ike@iceland.freeshell.org> - 2012-06-21 08:37 +0000
    Re: dequeue() not working Ike Naar <ike@iceland.freeshell.org> - 2012-06-21 08:42 +0000
      Re: dequeue() not working Ike Naar <ike@iceland.freeshell.org> - 2012-06-21 08:43 +0000
  Re: dequeue() not working Johann Klammer <klammerj@NOSPAM.a1.net> - 2012-06-21 11:09 +0200
    Re: dequeue() not working jgk@panix.com (Joe keane) - 2012-06-22 23:23 +0000
      Re: dequeue() not working Martin Shobe <martin.shobe@yahoo.com> - 2012-06-23 00:09 +0000
      Re: dequeue() not working Heikki Kallasjoki <fis+usenet@zem.fi> - 2012-06-23 00:10 +0000
      What's in a name? Johann Klammer <klammerj@NOSPAM.a1.net> - 2012-06-23 12:19 +0200
  Re: dequeue() not working Neil Cerutti <neilc@norwich.edu> - 2012-06-21 12:38 +0000
  Re: dequeue() not working pete <pfiland@mindspring.com> - 2012-06-23 00:39 -0400

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