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  1.  Home
  2. RPG400-L
  3. January 2011

RE: Memory allocation strategy

That is not specific to C. No "move list element" should have any trouble with reallocation as the memory of each element should be allocated individually, else it doesn't seem to be a classic linked list.

-----Original Message-----
From: rpg400-l-bounces@xxxxxxxxxxxx [mailto:rpg400-l-bounces@xxxxxxxxxxxx] On Behalf Of Elbert Cook
Sent: Sunday, January 09, 2011 6:56 AM
To: RPG programming on the IBM i / System i
Subject: Re: Memory allocation strategy

The only linked list, I've done was in C. There each List Element would
have 2 pointers, one pointer the Prior List Element, and one pointer to the
Next List Element.

If we moved a List Element, we had to change the pointers in both Adjacent
List Elements. But no pointer changes were required in the Moved List
Element itself.


-------- Original Message --------
From: "Rory Hewitt" <rory.hewitt@xxxxxxxxx>
Sent: Sunday, January 09, 2011 12:36 AM
To: "RPG programming on the IBM i / System i" <rpg400-l@xxxxxxxxxxxx>
Subject: Re: Memory allocation strategy

Ooh, good point, I hadn't thought of that... My linked list stuff uses
offsets rather than pointers, so it works either way...


On Jan 8, 2011 7:53 PM, "Elbert Cook" <elbert@xxxxxxxxxxxxxxx> wrote:

If you allocate 100 bytes of memory and for some reason, there is a
pointer
within those 100 bytes that points to a subset of itself.

Now you realloc to 200 bytes and the 100 bytes gets move to a
different
memory range.

Then the embedded pointer would still retain its original value and no
longer point to a subset of itself at the new location.

Lets not ask the question why someone would do that.


-------- Original Message --------
From: "Rory Hewitt" <rory.hewitt@xxxxxxxxx>
Sent: Saturday, January 08, 2011 8:45 PM
To: "RPG programming on the IBM i / System i" <rpg400-l@xxxxxxxxxxxx>
Subject: Re: Memory allocation strategy

Indeed, pointers in user-allocated memory are always retained, as far
as
I
know, even through multiple reallocations. If that weren't the case,
all
my
apps would fail...

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