Re: FOR loop limit

Has anyone brought up the DO loop with start value and limit value? Seems the issue of too small an index variable has been with us for some time.

Try this code in ILE RPG -

*C *1 DO 9 X 1 0
*C DSPLY X
C** ** **ENDDO

*

*Compile with TRUNCATE(*YES) and you get an infinite loop - with TRUNCATE(*NO) you get the overflow error. (***CMA************ disclaimer********** - ********
*I may have the parameter name wrong - hope y'all understand the intent)*
**
This was the earliest from of a FOR kind of loop that I'm aware of in my time on the system. Others have more history than I.

So IBM have never checked this kind of thing, it seems.

David, if you want to do something about it, submit a PMR (problem report or software service request) - see if IBM say it is by design or not - you will get a better answer from the people that make the compiler than from us, who are just guessing. Or submit a design change request (DCR).

Regards
Vern

David FOXWELL wrote:

Why don't we start at 0 like in other languages?

Eg,

For (int i=0 ; numberloops-1 ; i++)
Index= i + 1;


EndFor

What is the value of Index when the loop ends?





-----Message d'origine-----
De : rpg400-l-bounces@xxxxxxxxxxxx [mailto:rpg400-l-bounces@xxxxxxxxxxxx] De la part de Rory Hewitt
Envoyé : jeudi 29 janvier 2009 18:44
À : RPG programming on the IBM i / System i
Objet : Re: FOR loop limit

Jeff,

It's always been a pain like this. I assume there's some backwards-compatibility issue that made it work like this:

for x = 1 to 3;
...do something
endfor;

After the loop, x is 4, *not* 3.

If you step through in debug, you can see how it stops on the endfor after the 3rd time and then stops again on the endfor before moving on. It's documented in the RPG manual, but still it seems screwy to me. Couldn't they have added processing to not increment the counter after the last one (or to decrement it back again)?

Rory

On Thu, Jan 29, 2009 at 9:32 AM, Jeff Crosby <jlcrosby@xxxxxxxxxxxxxxxx>wrote:

I learned something new today.

Take the following program:

D x S 3P 0
D y S 3P 0

/free

*INLR = *On;
Y = 999;

For X = 1 To Y By 1;
EndFor;

Return;

/end-free


The program bombs with the dreaded "Message . . . . : The target for a
numeric operation is too small to hold the result (C G D F)."

I guess when the endfor is reached the last time through, it attempts
to set the value of x to 1,000.

Live and learn.

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