Redefines in cobol

l.nethaji · Posted: Fri Jan 08, 2010 8:31 pm

Hi,

01 WS-VAR1 PIC X(5).
01 WS-VAR2 REDEFINES WS-VAR1 PIC 9(3).
.
.

MOVE "HELLO" TO WS-VAR1.
DISPLAY WS-VAR1.
DISPLAY WS-VAR2.
.
.

will give out
HELLO
HEL

Please help me out what the logic happens behind and how the ws-var2 is HEL.

Thanks,
L.Nethaji

Bill O'Boyle · Posted: Fri Jan 08, 2010 8:37 pm

WS-VAR1 is FIVE bytes and WS-VAR2 is THREE bytes

The DISPLAY verb uses the length of the target field when performing the display.

Is this a trick question?

Robert Sample · Posted: Fri Jan 08, 2010 9:29 pm

It is a very common misconception that COBOL variables defined as PIC 9 can only contain numeric values. This is not true. A USAGE DISPLAY variable, such as you have defined as WS-VAR2, may contain numbers, letters, spaces, or special symbols. If you attempt to use that variable for arithmetic while it contains non-numeric data, you will get a S0C7 (usually) indicating non-numeric data in a numeric field. But just moving another variable into the variable and displaying the variable does not cause any issues in COBOL if the PIC 9 field does not contain numbers. This is not recommended since it is a bad coding practice but it is not, under COBOL's rules, illegal.

l.nethaji · Posted: Fri Jan 08, 2010 10:39 pm

Hi Robert,

I had a very clear understanding of redefines now .

Even i too had in mind like the variable declared as 9 should have numeric values.

Thanks a lot for ur reply,

l.nethaji

Robert Sample · Posted: Fri Jan 08, 2010 10:42 pm

Glad to hear it helped!

l.nethaji · Posted: Fri Jan 08, 2010 10:44 pm

Hi Robert,

I had a small clarification on the above

If ws-var1 has value 'ABC' and Ws-var2 had 123 .

What will be the value of both if we redefines as the same.

01 WS-VAR1 PIC X(5).
01 WS-VAR2 REDEFINES WS-VAR1 PIC 9(3).

According to my understanding the value of WS-VAR1 will be ' ABC' and the value of WS-VAR2 is 123.

Please correct if i am wrong . Parallely i will try testing it .

thanks,
L.nethaji

dbzTHEdinosauer · Posted: Fri Jan 08, 2010 11:15 pm

Mr. L.nethaji,

you seem to have a real problem with the REDEFINE clause used in COBOL.

redefines tells the compiler to map the memory differently than just previously defined.

WS-VAR1 is a 5 byte area.
WS-VAR2 is the first three bytes of WS-VAR1.

therefore, whatever is in one, is by definition in the other.

you really don't have to test anything. Read any COBOL Programmers Application Guide.

Robert Sample · Posted: Fri Jan 08, 2010 11:37 pm

l.nethaji · Posted: Fri Jan 08, 2010 11:55 pm

I missed to say that i just want to know if they are of same size

01 WS-VAR1 PIC X(3) value 'ABC'
01 WS-VAR2 REDEFINES WS-VAR1 PIC 9(3).

If ws-var1 has a initial value of ABC.then,the value of ws-var2 will be ABC .

In procedure division ,i am moving 123 to WS-VAR2.

In this condition the value of WS-VAR1 will be ABC and the value is WS-VAR2 is 123.

This is wat i meant to explain.
I just missed a lot in my previous post. Pls help if i am wrong based on this scenario.

Thanks for correcting me

Robert Sample · Posted: Sat Jan 09, 2010 12:03 am

Since you're not really paying attention to what you are being told, here is actual, tested COBOL code:

l.nethaji · Posted: Sat Jan 09, 2010 12:15 am

MAy be the way i explain things is not clear. Try to do my best next time.

YA i understand it well now.

" u meant to say the values are going to be the same for 2 variables if we redefine one with the other."

Thanks for the reply .

Robert Sample · Posted: Sat Jan 09, 2010 12:26 am

Just to cover all the bases, this code:

l.nethaji · Posted: Sat Jan 09, 2010 12:39 am

Hi,

On reading i am not able to get actually wat redefines does .
But i got it from ur examples .

Thanks for ur explaination on different cases.

Sure i got some new concepts learnt from my errors.

Robert Sample · Posted: Sat Jan 09, 2010 12:44 am

Glad to hear you've got it!