RE: Based variables

[Mark Drazic <Mark.Drazic@xxxxxxxxxxxx>]

Yes, you use ALLOC the 1st time, and REALLOC every record after that.  It
would help performance some to ALLOC 500 hundred records, though it seems
extremely fast just ALLOCating 1 record at a time.

> ----------
> From:         M. Lazarus[SMTP:mlazarus@ttec.com]
> Reply To:     RPG400-L@midrange.com
> Sent:         Friday, December 08, 2000 1:01 PM
> To:   RPG400-L@midrange.com
> Subject:      RE: Based variables
> 
> At 12/8/00 11:33 AM -0600, you wrote:
> >The way you do this is to NOT use a field, ONLY use a pointer that is
> first
> >Allocated to 1 record, and then Reallocated for an additional record each
> >time you read another record in.  This creates a completely dynamic and
> >contiguous memory block that holds the records for the file.  The
> externally
> >described Data Structure to the file is Based on a Pointer, and you
> >re-calculate this pointer to the correct position in the dynamic memory
> >block.
> 
>   Let me get this straight.  If the DS is based, the pointer is set for
> the 
> first record read.  I increment the pointer to point to the byte right 
> after the DS.  How do I know I'm not stepping on some valid data in 
> memory?  Do I use ALLOC / REALLOC to reserve it?  If yes, then that should
> 
> work well.
> 
>   Does it make sense (performance wise) to only add one record to the 
> memory allocation?  Or should I just add, say, 500 records worth.
> 
> 
> >Another technique in the RPG Programmer's guide is to create a Linked
> List.
> >The problem with this is that it requires at least 2 pointers per record,
> >and possibly 3, and creates a lot of pointer management issues.  The
> above
> >technique requires only 1 pointer for the data, and an additional pointer
> >for the Based Data Structure.
> 
>   I agree that a linked list is too complicated for this application.
> 
>   -mark
> 
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