Re: Dynamic arrays

[PaulMmn <PaulMmn@xxxxxxxxxxxxx>]

As an alternative, consider:

-- Create an array with a 'typical' number of records (ie your 'normal max').

-- Load the array at the start of your program.  If there are more records
than the (hard-coded) length of the file, set an indicator.

-- Set a variable with the number of records loaded into the array (in case
you have to do a sequential search of the array; you'll need to know where
to stop).

-- Lookup using the array.  If found, OK.  If not found, chain to the file
to make sure.

If you load the file with the most-used records first, this will save file
accesses.



As far as saving time by using arrays instead of files---  I dunno.  With
the single-level store, and paging of unused stuff to disk anyway, when
does a disk access become more 'expensive' than a table lookup?



--Paul E Musselman
PaulMmn@ix.netcom.com




>I have a work file (about 50 records) that is accessed very often by a RPG4
>program. I was thinking about reading the file into an array to make lookups
>faster. The problem is the file changes in size; sometimes it's 50 records,
>sometimes 60, or 40, etc. I'd like to create a dynamically-sized array at
>runtime. I briefly looked at the ALLOC/DEALLOC/REALLOC opcodes, but they
>really didn't make much sense.
>
>Is there a relatively easy way of creating dynamic arrays in RPG, or am I
>forced to create an arbitrary upper limit?
>
>Thanks,
>Loyd


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