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From: vallon@sboslab3.CS.SunySB.EDU (Justin Vallon)
Newsgroups: comp.sys.mac,comp.sys.mac.programmer
Subject: Re: Novice Programmer Question:  Dynamic Memory Allocation under TC
Message-ID: <4196@sbcs.sunysb.edu>
Date: 7 Dec 89 23:47:13 GMT
References: <24770@cup.portal.com>
Sender: news@sbcs.sunysb.edu
Reply-To: vallon@sboslab3.CS.SunySB.EDU (Justin Vallon)
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In article <24770@cup.portal.com>, David_Anthony_Guevara@cup.portal.com writes:
> [Porting an application from Vax to Mac]

Questions:
> When you use malloc to create a
> node (ex:  head = (struct linked_list *) malloc (sizeof( ELEMENT ));)
> does the memory allocated come from the stack or the application heap?

Application heap.  Otherwise, it would be deallocated when the function
returns.

> I believe my problem is that the Mac is relocating my pointers and the
> program just drops into a black hole.

Nope.  Malloc calls NewPtr, which will never relocate a block of memory
that it returns.  See Inside Mac chapter on the Memory Manager.

> No bomb, but it just sits there
> until I reset the system.  If the storage is allocated from the application
> heap, how can I make sure that nothing gets moved while the program is
> running?

It wont.  See above.

> I'm not using any toolbox calls, should I be?

No, you don't have to if you want to write a C (Object-C?) program.  The
Mac interface libraries make TC as close to "real" C as possible.

> As I said, the
> program DOES run on my VAX without any difficulty.  My configuration is
> a Mac Plus w/4Mb RAM, Think C 4.0, System 6.02 with assorted inits and cdevs.
> Thanks for any help you can give me!

Sorry that I couldn't give you any good news, but the problem must be in
you program.  Actually, one problem that I have a lot of times is
forgetting that malloc takes a long (32-bits).  ThinkC assumes an int
(16-bits) if no prototype is given.  See if malloc is being declared
as malloc(long), or put it in yourself:

Ptr malloc(long);

If that doesn't help, then feel free to send me mail directly.

> 	Dave Guevara,
> 	Internet:  guevara@fsd.arc.nasa.gov
>                    guevara@fsdvx2.arc.nasa.gov
>                    David_Anthony_Guevara@cup.portal.com

-Justin
vallon@sbcs.sunysb.edu