From:	ao950 AT FreeNet DOT Carleton DOT CA (Paul Derbyshire)
Newsgroups:	comp.os.msdos.djgpp
Subject:	Re: unused registers, realloc
Date:	4 Aug 1997 04:29:24 GMT
Organization:	The National Capital FreeNet
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Message-ID:	<5s3lr4$od1@freenet-news.carleton.ca>
References:	<m0wulJh-0003DjC AT fwd03 DOT btx DOT dtag DOT de> <rRqZABA47E5zEwZ0 AT talula DOT demon DOT co DOT uk>
Reply-To:	ao950 AT FreeNet DOT Carleton DOT CA (Paul Derbyshire)
NNTP-Posting-Host:	freenet5.carleton.ca
To:	djgpp AT delorie DOT com
DJ-Gateway:	from newsgroup comp.os.msdos.djgpp

Shawn Hargreaves (Shawn AT talula DOT demon DOT co DOT uk) writes:
> I'm not sure about the gcc malloc implementation, but I have in the past
> used compilers that did move the block around (it took me forever to
> work out why my code suddenly stopped working when I changed compiler!).
> It's probably not a good plan to assume that it will stay in the same
> place...

It is always a good idea to do one of two things with stuff you intend to
realloc:

1. Only use the one pointer to it; regenerate that pointer from realloc's
   return value.
Or if this is impractical:
2. Double indirection. Malloc or calloc to a whatever * pointer. Assign
   this pointer's address to a whatever ** pointer. Use that pointer
   everywhere, using (*(*pointer)) to access data. When realloc is used,
   assign its return value into the whatever * pointer; thus what is pointed
   to by all copies of the doubly indirect pointer will be the new address.
--
    .*.  Where feelings are concerned, answers are rarely simple [GeneDeWeese]
 -()  <  When I go to the theater, I always go straight to the "bag and mix"
    `*'  bulk candy section...because variety is the spice of life... [me]
Paul Derbyshire ao950 AT freenet DOT carleton DOT ca, http://chat.carleton.ca/~pderbysh

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