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Re: do I really understand this or not ?

From: Gregory Nicholls <gnicholls@level8.com>
Date: Thu, 08 Jun 2000 16:51:50 -0400
Message-ID: <39400766.65ED0746@level8.com>
To: www-lib@w3.org
  The last shall be first and the first shall be last. OK I can live with that.

    Thanks for the clarification
        G.
(who still has to figure out why he got a NULL return from the original code)

"Desrochers, Gary" wrote:

> No, the routine is right.  The HTList is in backwards order so that the
> first item in the list is at the end of the chain.  The last item in the
> list is the first in the chain.  (Unless it was sorted.)  While there is
> extraneous code, the code is right.  It looks like it is copied from the
> HTList_removeFirstObject routine above it.  If you remove the extraneous
> stuff you get:
> PUBLIC void * HTList_firstObject  (HTList * me)
> {
>     if (me && me->next) {
>         while (me->next)
>             me = me->next;
>         return me->object;
>     } else
>         return NULL;
> }
>
> Your routine is actually returning the last object in the list.  This would
> be the routine which does not exist called HTList_lastObject:
> PUBLIC void * HTList_lastObject  (HTList * me)
> {
>     if (me && me->next)
>      {
>       return me->next->object;
>      }
>     return NULL;
> }
> -----Original Message-----
> From: Gregory Nicholls [mailto:gnicholls@level8.com]
> Sent: Thursday, June 08, 2000 3:00 PM
> To: www-lib@w3.org
> Subject: do I really understand this or not ?
>
> Hi,
>  I've found something odd with the HTList_firstObject() function. My
> read on this is that it should return a pointer to the first object in
> the list. Running some tests shows that this doesn't happen.
>   After looking at the source it seems (to my naive eye) that this
> routine will always return NULL.
>     Here's the source I have with a mod that I put in to make it work
> the way I _think_ it's supposed to.
> Could someone more knowledgable please comment on this please ?
>
>     Thanks,
>         G
> --------------- snip -----------------------
> PUBLIC void * HTList_firstObject  (HTList * me)
> {
> /* This is the original code
>     if (me && me->next) {
>         HTList * prevNode;
>         while (me->next) {
>             prevNode = me;
>             me = me->next;
>         }
>         return me->object;
>     } else
>         return NULL;
> */
> /* This is my new stuff */
>     if (me && me->next)
>      {
>       return me->next->object;
>      }
>     return NULL;
> }
Received on Thursday, 8 June 2000 16:48:53 GMT

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