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shekar123 · Posted: Wed Nov 02, 2005 4:55 pm Post subject: redefines clause display

Hai all,

I have coded in my pgm and i get the output as below.But i am not able to figure out how exactly the redefines has taken effect and i am not clear with how the output which has come .Can anybody guide me with the solution ?

Code:

01 GROUPA.
05 X PIC S9(4) VALUE +123.
05 Y REDEFINES X.
10 X1 PIC X.
10 X2 PIC X.

OUTPUT
---------

Code:

X1 IS 0
X2 IS 1

My understanding is that variable X takes 4 bytes of storage as 9(4) and sign is punched over the last nibble bits so it will take the form

---------
0|1|2|3
---------

Now Y is redefined and it also takes 4 bytes of storage and it will take the form and since X1 and X2 are alphanumeric they take from the left most bits individually.

---------
0|1|2|3
---------
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Shekar
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SureshKumar · Intermediate Joined: 23 Jan 2003 Posts: 211 Topics: 21

shekar123,
your Y is only 2 bytes ?

kolusu · Posted: Wed Nov 02, 2005 6:07 pm Post subject:

shekar123,

Check these topics which will answer your questions

http://www.mvsforums.com/helpboards/viewtopic.php?t=3415&highlight=display

http://www.mvsforums.com/helpboards/viewtopic.php?t=2099&highlight=numproc

Hope this helps...

Cheers

Kolusu
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Ravi · Beginner Joined: 27 Jun 2005 Posts: 88 Topics: 2

Mervyn · Posted: Wed Nov 02, 2005 7:15 pm Post subject:

SureshKumar has the correct answer.

You're only redefining the first two bytes, which contain '01'.

Cheers,
Merv
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semigeezer · Posted: Wed Nov 02, 2005 10:35 pm Post subject:

Wait a minute. Am I missing something? I don't know COBOL well, so are you saying that COBOL stores signed decimal as a the EBCDIC representation of a packed decimal number? That sounds absolutely crazy! That would mean that for every arithmetic operation, it not only has to do a CVB and convert to decimal (or more likely use the packed arithmetic instructions), but it also has to do a PACK and UNPK? And it wastes 1/2 the available space. Why doesn't it store it as a packed decimal or is that a different COMP type? (Its been years since I did anything with packed decimal; I never really had a need for it, so my memory may be terribly wrong about how things work).

kolusu · Posted: Thu Nov 03, 2005 5:39 am Post subject:

semigeezer,

Here is a link which explains the internal storage reprenstation of numeric items in cobol

http://publibz.boulder.ibm.com/cgi-bin/bookmgr_OS390/BOOKS/IGY3PG10/1.3.4.7?DT=20020923143836

Kolusu
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Dibakar · Posted: Thu Nov 03, 2005 6:06 am Post subject:

Semigeezer,

Packed data are comp-3. In this case, S9(4), I don't think CVB will be required, only L and AR should do. I will look at some compilation listings to verify.

semigeezer · Posted: Thu Nov 03, 2005 12:56 pm Post subject:

Thanks to both of you. I'll run a compile w/ the LIST option later today to check.

Dibakar · Posted: Sat Nov 05, 2005 5:20 am Post subject:

I finally got time to compile a program with S9(4) and S9(4) COMP-3.

Here is what I found -

Dibakar · Posted: Mon Nov 07, 2005 4:46 am Post subject:

I am adding two more on my friend's request.