Article View: comp.std.c
Article #394Re: (char *)(-1)
From: david Fridley
Date: Mon, 31 Jul 1989 06:38
Date: Mon, 31 Jul 1989 06:38
35 lines
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1570 bytes
In article <18792@mimsy.UUCP>, chris@mimsy.UUCP (Chris Torek) writes:
> >>... if NULL is returned there was an error getting the next string,
> >>if (-1) is returned there were no more symbols.
>
> >Is it safe to return -1?
>
To quote from the my UNIX System V (Release 3.0) Programmers Reference manual
for BRK(2) (page 141):
NAME
brk,sbrk - change data segment allocation
SYNOPSIS
int brk (endds)
char *endds;
char *sbrk (incr)
int incr;
:
:
DIAGNOSTICS
Upon successful completion, brk returns a value 0 and sbrk returns the old
break value. Otherwise, a value of -1 is returned and errno is set to
indicate the error.
Here we see that sbrk(), a standard UNIX function, which returns a character
pointer will return (-1). This is the functioin used by malloc() to get
free more free memory from the operation system.
--
david.
DISCLAIMER: If it's important have a backup. If it ain't broke don't fix it.
Proceed at your own risk. My oponions are MY own. Spelling does not count.
My fondest dream is to leave this planet.
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arc1-ca.pugleaf.net!utzoo!attcan!utgpu!jarvis.csri.toronto.edu!mailrus!csd4.milw.wisc.edu!cs.utexas.edu!uunet!psitech!davidReferences:
<GEOFF.89Jun11231924@onyx.cs.warwick.ac.uk> <2619@yunexus.UUCP> <18792@mimsy.UUCP>Show Full Headers
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Path: arc1-ca.pugleaf.net!utzoo!attcan!utgpu!jarvis.csri.toronto.edu!mailrus!csd4.milw.wisc.edu!cs.utexas.edu!uunet!psitech!david From: david@psitech.UUCP (david Fridley) Newsgroups: comp.std.c Subject: Re: (char *)(-1) Summary: char *sbrk(); Keywords: pointers, casts Message-ID: <120@psitech.UUCP> Date: 31 Jul 89 06:38:36 GMT References: <GEOFF.89Jun11231924@onyx.cs.warwick.ac.uk> <2619@yunexus.UUCP> <18792@mimsy.UUCP> Organization: PsiTech Inc., Fountain Valley, CA Lines: 35