Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!mailrus!cornell!rochester!kodak!gizzmo!lazlo!mobile!dave
From: dave@mobile.UUCP (David C. Rein)
Newsgroups: comp.unix.wizards
Subject: Re: Referencing NULL pointers
Summary: What about portability?
Message-ID: <176@mobile.UUCP>
Date: 12 Jul 89 17:38:37 GMT
References: <19367@paris.ics.uci.edu> <1891@auspex.auspex.com> <32UP02Eg3d=801@amdahl.uts.amdahl.com>
Lines: 34

In article <32UP02Eg3d=801@amdahl.uts.amdahl.com>, vohra@uts.amdahl.com (Pavan Vohra) writes:
> In article <1891@auspex.auspex.com> guy@auspex.auspex.com (Guy Harris) writes:
> >>   Apparantly, on other machines this is perfectly valid, since I see
> >>   quite a lot of this in code created on certain non-sun machines.
> >
> >No, it's not valid, it just happens to work - and only on *some* other
> 
> I would say that the code is valid.
> [..stuff deleted..]
> Anyway, it is the operating system that makes the action that the
> process takes valid or invalid.
> 
> KC borrowing vohra

   Well, since the operating system we are discussing here is *NIX, 
   I don't understand your comment of 'the operating system that makes the 
   action...valid or invalid', or are we just dropping the idea of
   portability?  The fact that you might be able to access 0 is meaningless.
   In AIX PS/2, if you do a (i.e.) printf("%s", (char *)0); you'll get:

   L

   since this is the magic number for AIX executables.  Basically, a program
   that makes the assumption that it can dereference possibly uninitialized
   pointers is not a well written program (in my opinion).  And, most
   important of all, since not all *NIX systems allow for this (as they should
   not!), it hinders the portability of code, which is one of the foundations of
   *NIX!
                                                        Dave Rein
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