Hi Nancy
I think you are thinking of the difference between RPG III (RPG400 in
your terms) and RPG IV. I'll start with that assumption
Some opcodes were slightly modified in RPG IV - usually made longer.
Here is something from a manual on moving to RPG IV - "Some of the
existing operation codes are renamed to improve
readability and better understanding of the program code."
1. In RPG III, the column width for opcodes is 5 and operation extenders
like half-adjust are in a column immediately after the result column
data type definition.
2. In RPG IV, the column width for opcodes is 10, which now includes
room for the operation extenders. The max length of opcodes is now 6 (I
think) instead of 5.
So an opcode like UPDAT in RPG III is now UPDATE in RPG IV.
According to that manual, only 15 opcodes were renamed - so BITOF became
BITOFF - much more readable. EXCPT became EXCEPT. WHxx became WHENxx.
So that's enough on that. What about free format?
Well, the original RPG IV (V3R1 of the OS in 1995) had a start on free
format with the H-spec. It also started out in C-specs with the extended
factor 2, where free-format arithmetic and logical expressions are
allowed - that column is 45 wide. It's used with the new opcodes like
EVAL, IF, WHEN, DOU, & DOW. Things like IF allow much more freedom in
stating the condition, compared to row upon row of IFxx and ANDxx and
ORxx opcodes - I don't think I've consciously used any of those old
constructions for years.
Now along comes full free-format calculation specs. What you do with
these is specify only the operations. You don't have the result
data-type columns, nor result-indicator columns. These latter items are
done elsewhere, in D-specs (declaring of variables) and with built-in
functions for things like the EQUAL status after SETLL or FOUND status
after CHAIN or LOOKUP. It actually gets a much cleaner look. I know I
never remember now which of the resulting indicators applies to which
operation. Until I look at old code, so then I get a format line at the
top of the editor in RDi - very cool.
Now to your supposition - actually, free-format has exactly the same
opcodes as fixed-format. There will be differences in the order of
things that were in Factor 1 and Factor 2 and Result columns.
When you look at an opcode in the ILE RPG Reference, there will be both
the fixed form and the free-form equivalent presented.
I dare say, if only for the nifty date-handling operations we now have,
that is a sufficient reason to move to RPG IV and eventually free-format.
The document, "Moving to ILE for RPG IV", is a redbook from 1995 - I
think it's a great resource for getting started on this - here's a link
to it -
www.redbooks.ibm.com/abstracts/gg244358.html?
Free-format first appeared at V5R1 of the OS - so I recommend going to
any of the Infocenters and getting the ILE RPG Reference. If you want to
look at history, the V5R1 Infocenter is at -
http://publib.boulder.ibm.com/iseries/v5r1/ic2924/info/rzahgicmain.htm
The latest version is at -
http://publib.boulder.ibm.com/infocenter/iseries/v7r1m0/index.jsp
ILE RPG (RPG IV) appeared first at V3R1 - if interested, here's a link
to the V3R2 manuals - more historical interest, perhaps -
http://publib.boulder.ibm.com/pubs/html/as400/online/v3r2.htm
Anyhow, there's a long reply to your short observation!! I hope it's
helpful.
Happy Thanksgiving!
Vern
On 11/28/2013 8:01 AM, newnancy@xxxxxxxx wrote:
I never understood the difference of regular RPG400 and free form RPG.
Supposedly they do not have the same opcodes.
Thank you,
Nancy
On Wed, 27 Nov 2013 19:12:38 -0600 "Jerry C. Adams" <midrange@xxxxxxxx>
writes:
Never understood what, Nancy?
[Nice name, by the way. Same as my little sister, and first girl
friend -
2nd grade. Different people, of course. .-) ]
Jerry C. Adams
IBM i Programmer/Analyst
People think I'm too patronizing. (That means talking down to
people.)
--
Home Office: 615-832-2730
email: midrange@xxxxxxxx
-----Original Message-----
From: rpg400-l-bounces@xxxxxxxxxxxx
[mailto:rpg400-l-bounces@xxxxxxxxxxxx]
On Behalf Of newnancy@xxxxxxxx
Sent: Tuesday, November 26, 2013 8:10 AM
To: rpg400-l@xxxxxxxxxxxx
Cc: rpg400-l@xxxxxxxxxxxx
Subject: Re: INLR no longer required?
This is really before my time, and I started programming in the
early 1990s.
Now are most of you using free form RPG or not? I never really
understood
the difference.
Thank you,
Nancy
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