Re: simple questions-cannot find answers in common books

[Buck Calabro/commsoft<mcalabro@xxxxxxxxxxxx>]

James Kilgore wrote:

>Some of your books may be too new to bother covering #1 
>and #2 ;-)

The best answer to these questions depends on the reason
for asking.  If you're trying to read some old programs and
understand what they do, then I'd completely agree with
the answers posted so far.  If you're trying to write a
brand new program using these, I'd probably advise you
to find another way.

>christopher sagayam wrote:
>
>> in rpg programming
>>
>> 1.in form type I what is the use of SEQUENCE  eg.AA etc
>
>Back in the "old" days, especially when cards were king, if 
>your file required a header record with 'n' detail records 
>for each logical group of entries, this was a way to sequence 
>check your input.  If a card was out of order, a halt would be
>issued.

If you put numbers in those columns, your input records get
sequence checked.  If you put characters in there (like "AA"
or "NS" then no sequence checking is done.  That would be
more typical now.

>> 2.how are indicators U0-U9,MR used.
>
>I've only heard of U1-U8, but I'll bet your book just says Ux 
>indicators, anyway these indicators (also referred to a "switches") 
>were created again back in the "old" days for inter program 
>communication.  Program A could turn a switch off/on
>so that when program B executed, some "state" or result of 
>program A could be determined.

On the AS/400 you turn these switches on/off in RPG just like
any other indicators.  In CL you use CHGJOB SWS(10001000) to
turn on switches 1 and 5.

-snip-

>Although the RPG cycle and MR processing are not in flavor 
>today, IMHO it's still one of the better ways to blast through
>files.

There's a provocative statement!  There are only a very few
people who are comfortable with matching records programs - 
basically us "geezers" who started our MIS careers using cards.
Nowadays, there are only a tiny number of situations where MR
is needed - OPNQRYF and SQL have done a good job replacing it.
I will say this: when you need MR, you need it BAD!

>> 3.is there any way i can try out RPG programs using internet ie
>> downloading or etc.

There are only a few sites where source code is posted, and I 
can't think of any places you can find object code.  Try
http//www.midrange.com and
http://www.midrangecomputing.com and 
http://www.news400.com

>> 4.can a subfile be used to access data from different 
>>physical files if so how can an update pgm work on 
>>different physical files.

Subfiles may be the worst named concept on the AS400.
A subfile is nothing more than a display method whereby
you write multiple similar records onto the display.  An
example of this might be all the items on your Sears
credit card bill.  Each purchase is a different "item",
but they all have the same format: date, product name,
amount.

May I suggest going to http:www.midrange.com and following
the link to "books" and order one or two books on RPG400?
I think you'll find it easier to grasp some of these concepts
when you see them in print, and presented all together rather
than piecemeal through email...  Also, you can read all the
AS/400 manuals on the internet at 
http://as400bks.rochester.ibm.com/

Buck Calabro
CommSoft, Albany, NY
mailto:mcalabro@commsoft.net




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