Re: Based variables

[Jim Langston <jimlangston@xxxxxxxxxxxxxxxx>]

Hmm.. no.

The pointer will point to the start of the Data structure.  This data
structure initially contains one record.  Say the data structure is 240
bytes long.  When you read anther record, you allocate another 240 bytes
to store it in, which goes at the end of your first record.  Then you
increment your pointer by 240, so now it will be pointing at the start
of the second record.

Regards,

Jim Langston

"M. Lazarus" wrote:
> 
> 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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