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Article View: comp.std.c
Article #395

Re: (char *)(-1)

#395
From: Michael Zehr
Date: Mon, 31 Jul 1989 15:21
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Someone, somewhere, somewhen, asked:
>Is it safe to return -1?

In article <120@psitech.UUCP> david@psitech.UUCP (david Fridley) writes:
>To quote from the my UNIX System V (Release 3.0) Programmers Reference manual
>for BRK(2) (page 141):
>[brk,sbrk definitions]
>
>Here we see that sbrk(), a standard UNIX function, which returns a character
>pointer will return (-1).  

Giving an example of software that does not conform strictly to the
dpANS standard for C is not an argument for writing more software like
it.  Not only is returning (char *) -1 (or (void *) -1) not safe for
portability reasons, it's also not a very good programming practice.

The practice of returning zero to indicate failure of some sort is very
firmly entrenched in software development, so go ahead and use that
method -- but don't make it any worse.  If you must return errors like
this, follow the current practice -- 0 (or (void *) 0) means error, with
more detail in a global error code (errno, for example).

It's taken long enough to get a dpANSI standard -- let's at least use it
now!

-michael j zehr
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Message-ID: <13161@bloom-beacon.MIT.EDU>
Path: arc1-ca.pugleaf.net!utzoo!attcan!utgpu!jarvis.csri.toronto.edu!mailrus!csd4.milw.wisc.edu!cs.utexas.edu!usc!bloom-beacon!athena.mit.edu!tada
References: <GEOFF.89Jun11231924@onyx.cs.warwick.ac.uk> <2619@yunexus.UUCP> <18792@mimsy.UUCP> <120@psitech.UUCP>

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Path: arc1-ca.pugleaf.net!utzoo!attcan!utgpu!jarvis.csri.toronto.edu!mailrus!csd4.milw.wisc.edu!cs.utexas.edu!usc!bloom-beacon!athena.mit.edu!tada
From: tada@athena.mit.edu (Michael Zehr)
Newsgroups: comp.std.c
Subject: Re: (char *)(-1)
Keywords: pointers, casts
Message-ID: <13161@bloom-beacon.MIT.EDU>
Date: 31 Jul 89 15:21:11 GMT
References: <GEOFF.89Jun11231924@onyx.cs.warwick.ac.uk> <2619@yunexus.UUCP> <18792@mimsy.UUCP> <120@psitech.UUCP>
Sender: daemon@bloom-beacon.MIT.EDU
Reply-To: tada@athena.mit.edu (Michael Zehr)
Organization: Massachusetts Institute of Technology
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