Path: utzoo!utgpu!news-server.csri.toronto.edu!mailrus!uwm.edu!ogicse!oregon!jmeissen
From: jmeissen@oregon.oacis.org (John Meissen)
Newsgroups: comp.sys.amiga.tech
Subject: Re: De-Allocating Memory?
Keywords: Lattice 5.04?
Message-ID: <492@oregon.oacis.org>
Date: 9 May 90 19:05:02 GMT
References: <12750@wpi.wpi.edu> <X-8#!|_@masalla.fulcrum.bt.co.uk>
Organization: Oregon Advanced Computing Institute (OACIS), Beaverton, OR
Lines: 27

In article <X-8#!|_@masalla.fulcrum.bt.co.uk> S.J.Raybould@fulcrum.bt.co.uk (Simon Raybould) writes:
>You need a recursive routine to free the whole list, along the lines of
>
>freelist(ptr)
>struct listelement *ptr;
>{
>	if(ptr->Next)
>		freelist(ptr->Next);	/* Recurse */
>	if(ptr)
>		free(ptr);
>}
This is exactly the routine the original poster had listed, except he didn't
bother to check the validity of 'ptr' before freeing it. In that respect,
your routine has a bug, because if there is a chance of the pointer being
invalid you should check it BEFORE dereferencing it:

	if (ptr)
	   {
	   if (ptr-Next) freelist(ptr-Next);
	   free(ptr);
	   }

-- 
 John Meissen ............................... Oregon Advanced Computing Institute
 jmeissen@oacis.org        (Internet) | "That's the remarkable thing about life;
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