doubt in PERFORM VARYING...

Ajay Baghel · Posted: Mon Dec 24, 2007 6:29 pm

I have a doubt in PERFORM VARYING...

Does changing the counter variable inside the execution range affect the no of the iterations?

stodolas · Posted: Mon Dec 24, 2007 6:34 pm

Don't mess with your look varbiables outside of the control statement if you can help it. Otherwise use a continue/no continue flag and just set to no when you want to stop. But adding different values than the BY 1 statement makes for crappy tracing when someone else tries to figure out what is going on.

Ajay Baghel · Posted: Mon Dec 24, 2007 6:41 pm

I know it is not a good way of programming. But I had taken one test and these type of questions were there.

Thanks,
Ajay

murmohk1 · Posted: Mon Dec 24, 2007 7:11 pm

Ajay,

abhishekmdwivedi · New User Joined: 22 Aug 2006 Posts: 95 Location: india

Ajay,

The variables used under loops for iteration purpose when manipulated under the performing para or statements are not reflected in the no. of iterations performed.
As the loop doesn't allow the control of the iteration variable to be used under the looped statements or para.

So,

ksk · Posted: Wed Dec 26, 2007 2:47 pm

Hi Abhishe,

9 is wrong if K wil not be affected by the the ADD statment.

abhishekmdwivedi · New User Joined: 22 Aug 2006 Posts: 95 Location: india

Well KSK,

if you check.

ksk · Posted: Wed Dec 26, 2007 4:35 pm

Hi Abhishek,

You are right. K starts from 1 and increments by 1.

When K value becomes 10, conditon becomes false, so it would be executed. when K becomes 11, i.e. 10 times, condition becomes true and control comes out of the perform.

So, it perfroms 10 times.

That's what I have thought and written.

abhishekmdwivedi · New User Joined: 22 Aug 2006 Posts: 95 Location: india

KSK,

You are right man for

ksk · Posted: Wed Dec 26, 2007 5:15 pm

Abhishek,

Ajay Baghel · Posted: Wed Dec 26, 2007 6:55 pm

rahul.banik · New User Joined: 23 Jan 2007 Posts: 16 Location: Mysore

Hi Ajay,

Better way to check this is just display the 'k' within the 0100-PARA and
after the Perform stament.I think ADD 2 TO K will affect the no. of iterations.

Douglas Wilder · Posted: Thu Dec 27, 2007 9:59 pm

The best way to know the answer is to test it.

akkireddy · New User Joined: 13 Jul 2007 Posts: 1 Location: hyd

no change in that itterations...

stodolas · Posted: Thu Dec 27, 2007 11:56 pm

This is flat out wrong.... did you even test this?
[quote]
The variables used under loops for iteration purpose when manipulated under the performing para or statements are not reflected in the no. of iterations performed.
As the loop doesn't allow the control of the iteration variable to be used under the looped statements or para.
[/code]

Douglas is correct as he shows with his test restuls. It does change the number of iterations. Cobol by default treats all working storage fields as global. Since K is a global working storage field, any modification of it will affect another part of the program.

Instead of 10 iterations, you will see only 4 iterations.

ksk · Posted: Fri Dec 28, 2007 10:20 am

Hi,

Yes, douglas is correct. Perform is done only 4 times. Modifying the counter afftected the number of iterations.

JAGAN_SRIRAM · New User Joined: 21 Jul 2007 Posts: 4 Location: INDIA

no the value of the variable will not be changed until the perform is completed. explanation for this question is available in ibm interview questions

ksk · Posted: Fri Dec 28, 2007 12:22 pm

Hi,

Following is the code:

ahalyah · New User Joined: 13 Dec 2007 Posts: 25 Location: india

Hi,
i also agree with Douglas

Douglas Wilder · Posted: Fri Dec 28, 2007 9:58 pm

JAGAN_SRIRAM, Do you believe ANY Web sight more than what the computer acutlly does? Try it yourself! What does the computer actually do? I already took the few minute to test it and posted my results.

If you provide a link we can check if you are misunderstanding the interview question or answer or if the question or answer is actualy wrong.

Of course, if that is the answer the interviewer is looking for, you can decide for yourself if you want to give the interviewer the correct answer or the answer they are looking for. It is not always a good idea to try to educate an interviewer during the interview, even if they are wrong.

Ajay Baghel · Posted: Sat Dec 29, 2007 3:52 pm

Thanks everybody for such a prompt discussion.

As mentioned in my original message, i don't have access... so i could not test it.

I conclude from the test results that :

"Changing the iteration variable within the range of PERFORM does affect the final no of iterations. Also the iteration variable gets modified."

Thanks.
Ajay