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From: lopez@uiucdcsp.cs.uiuc.edu
Newsgroups: comp.lang.c
Subject: Re: To comment 48: Xenix
Message-ID: <77200001@uiucdcsp>
Date: Fri, 24-Apr-87 20:16:00 EDT
Article-I.D.: uiucdcsp.77200001
Posted: Fri Apr 24 20:16:00 1987
Date-Received: Sun, 26-Apr-87 22:08:17 EDT
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Nf-ID: #N:uiucdcsp:77200001:000:1386
Nf-From: uiucdcsp.cs.uiuc.edu!lopez    Apr 24 19:16:00 1987


Reply to Xenix Comments by Dave.

Being a User of Microport's Unix System V I don't have to deal with
the madness of Microsoft.

The problem of having pointers that are not the same length as integers
cost me a day and alot of steam. But I think that declaring:

#define NULL (char *)0

is expensive but will always do the trick for all models (small,large,huge)

On UNIX System V AT I had done the typical tricks in C of:

   if (!charptr)

   Even though I new it was crypt, but efficient.

   But all of that worked while I was in the small memory model, when
   I went to large I core dumped my brain.

   For now pointers were 32 bits instead of 16 bits, 
   but integers are 16 bits.

   So after alot of frustration I figured out that NULL was defined
   as 0L. Which makes sense since we need a 32 bit zero value, which
   is not an integer.

   But As for people saying that if (charptr == 0) should work,
   "for any good C programmer's" I think thats hogwash.

   On every system I have ever used if (!charptr) worked,
   but I am happy that System V/AT has finally forced me to
   write code that is less crypt.

   if (charptr == NULL)

   is easier to read by everyone, and less likely to be a source of 
   unexpected bugs.

   As for Microport's product, I think it is the real McCoy. Xenix
   is for people who have no class.

   Frank Lopez
   University of Illinois