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Hi Brent,
This is great advice from James.
I've been writing in RPG for the last 37 years and started out with the RPG Cycle. Having written in Assembler & Cobol before, it was hard to understand, but once you grasp that you don't need to worry about Opening & Closing files and other mundane programming tasks, it becomes very useful. Send any messages my way and I will be only too happy to help.
One area that I am very poor on is developing programs using sub-files with interactive screens.
Rgrds,
Alan McKenzie
XA Consultant
CBI electric Telecom Cables (Pty) Ltd.
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From: RPG400-L [mailto:rpg400-l-bounces@xxxxxxxxxxxx] On Behalf Of
James H. H. Lampert
Sent: 27 April 2017 06:39 PM
To: RPG programming on the IBM i (AS/400 and iSeries)
<rpg400-l@xxxxxxxxxxxx>
Subject: Re: New to RPG
The only thing I can think of to add is this:
DON'T BE AFRAID TO TAKE A RIDE ON "THE CYCLE."
Because of RPG's history (it's name means "Report Program Generator"),
it's designed to process entire files, and as such, every RPG program
(unless, in the more recent versions of RPG, you explicitly disable
it) runs inside an implicit "DO UNTIL *INLR = TRUE" loop, and if you
designate a file as the "Primary File," each iteration of that
implicit do-loop begins with a read operation on that file, raising the "LR"
indicator when the last record of the file is read.
If you designate a Primary File, then The Cycle allows you to "ride"
through the file, processing each record in sequence, instead of
having to "walk" through it.
And if you don't designate a Primary File, then The Cycle can be used
as a built-in event loop for an interactive program: all you need to
do is raise the LR indicator whenever the user is ready to exit.
If you don't have a use for The Cycle in a given program, then you
need to either disable it explicitly, or else make sure LR gets raised.
WHAT YOU DO NOT WANT TO DO IS IGNORE "THE CYCLE." If you ignore The
Cycle, it will run over you.
--
JHHL
--
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