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Mail Archives: djgpp/1999/07/20/05:05:27

From: "Michael Stewart" <mike AT reggin DOT freeserve DOT co DOT uk>
Newsgroups: comp.os.msdos.djgpp
Subject: Re: A Structured Problem ?
Date: Tue, 20 Jul 1999 09:32:21 +0100
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To: djgpp AT delorie DOT com
DJ-Gateway: from newsgroup comp.os.msdos.djgpp
Reply-To: djgpp AT delorie DOT com

Paul J G wrote in message <7n09p0$9db$1 AT news5 DOT svr DOT pol DOT co DOT uk>...
>Many thanks to everybody, everythings running fine now. Although perhaps
you
>could be so kind as to answer these questions for me.
>
>1) How would I use the free command to free up one of the shape
indentifiers
>or to delete
>    the whole structure ?.

To delete a structure created with malloc you use the free function.

char *test;
test = (char *) malloc (10);
...
free (test);

So using your shape variables

free (shape[shape_no].xpoint);
free (shape[shape_no].ypoint);

>2) Both Michael and Ed used slightly different malloc commands, whats the
>difference ?.


The code I posted used a cast to tell the compiler that the allocated memory
will be used as float*. Ed didn't use a cast.

malloc returns void* and by using a cast it'll prevent the compiler
complaining about converting between types. It should be quite safe to use
the memory without the cast though.

>3) If I am writing for a machine with 32 megs and want to use, say 3 megs
>for holding my shape data in would I use FARMALLOC command instead ?.


Nope. (from the FAQ) In DJGPP you use a flat address space with no
segmentation, so you don't need far pointers in the sense they are used in
16-bit code.

So if you want to allocate 3mb the all you need to do is:

char *bigmem;
bigmem = (char *) malloc (3 * 1024 * 1024);

Michael Stewart


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