Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!ames!lll-winken!uunet!kddlab!titcca!sragwa!wsgw!socslgw!diamond!diamond
From: diamond@diamond.csl.sony.junet (Norman Diamond)
Newsgroups: comp.lang.c++
Subject: Re: Possible error in Stroustrup ?
Message-ID: <10330@socslgw.csl.sony.JUNET>
Date: 5 Jun 89 05:12:59 GMT
References: <774@batserver.cs.uq.oz>
Sender: news@csl.sony.JUNET
Reply-To: diamond@csl.sony.junet (Norman Diamond)
Organization: Sony Computer Science Laboratory Inc., Tokyo, Japan
Lines: 40

In article <774@batserver.cs.uq.oz> anthony@batserver.cs.uq.oz writes:

>On page 205 of "The C++ programming language" by Stroustrup, there is 
>listing of a get function for circular list class slist.

>ent slist::get()
>{
>   if (last == 0) slist_handler("get from empty slist");
>   slink* f = last->next;
>   ent r = f->e;
>   last = (f==last) ? 0 : f->next;
>^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
>   delete f;
>   return r;
>}

>The line starting with "last = ...." seems to be wrong.  The function
>get is suppose to return and remove the head of the list.
>Can anyone confirm this ?

Looks to me like it was a bug, and it looks to me like it looked to
Bjarne Stroustrup like it was a bug, too.  In my copy of The Book, it
now looks like:

if (f == last)
    last = 0;
else
    last->next = f->next;

I guess it is no longer nececessary to get the wrong answer in as few
lines as possible.

Once upon a time, someone suggested testing examples before publishing
them.  Does no one learn?

--
Norman Diamond, Sony Computer Science Lab (diamond%csl.sony.co.jp@relay.cs.net)
  The above opinions are my own.   |  Why are programmers criticized for
  If they're also your opinions,   |  re-implementing the wheel, when car
  you're infringing my copyright.  |  manufacturers are praised for it?