Add statement, what is the value of A

rajrohith · New User Joined: 15 Apr 2005 Posts: 54 Location: chennai

i have one doubt in add statement
for example

01 a pic 9

add -2 to a.
add -4 to a.
add -6 to a.

i want to know what is the value of A right now

thanks
raj

William Thompson · Posted: Tue Dec 19, 2006 9:17 pm

What do you think it is?

rajrohith · New User Joined: 15 Apr 2005 Posts: 54 Location: chennai

my interviewer asked this question
but i didnt try this example

jcbhimani · New User Joined: 30 Nov 2006 Posts: 12 Location: Ahmedabad

In my view -6 will be added to the old value of a and stored in a.

William Thompson · Posted: Tue Dec 19, 2006 9:23 pm

well, just for fun, give it a try, and explain to me how you arrived at your answer....

jcbhimani · New User Joined: 30 Nov 2006 Posts: 12 Location: Ahmedabad

If we have not mentioned any initial value for a then I think some garbage value will be there and -6 will be added to that.

Please give me correct answer.

I am curious to know it......................

William Thompson · Posted: Tue Dec 19, 2006 9:31 pm

well, for the sake of argument, assume that it was initialized to zero, what is its value after the adds?

rajrohith · New User Joined: 15 Apr 2005 Posts: 54 Location: chennai

i told just 6 only
because if we specify sign we will see -6
but in this example we didnt specify any sign
so what is the value of a
by
raj

jcbhimani · New User Joined: 30 Nov 2006 Posts: 12 Location: Ahmedabad

see it the initial value is 0 then in first operation value of a will be -2 then -6 and finally -12.

jcbhimani · New User Joined: 30 Nov 2006 Posts: 12 Location: Ahmedabad

I think I am wrong because a is specified as PIC 9 so how can -12 be stored.

rajrohith · New User Joined: 15 Apr 2005 Posts: 54 Location: chennai

i accept that answer but can we see the minus sign
by
raj

William Thompson · Posted: Tue Dec 19, 2006 9:38 pm

I think that:
0+-2=-2 but there is no sign so now a=2
2+-4=-2 but there is no sign so now a=2
2+-6=-4 but there is no sign so now a=4

final answer? 4

rajrohith · New User Joined: 15 Apr 2005 Posts: 54 Location: chennai

thanks for ur reply
raj

dick scherrer · Posted: Tue Dec 19, 2006 9:42 pm

Hello,

The code as shown may very well get a S0C7. "a" doesn't have an initial numeric value. You may get strange results if there happens to already be some number at that location.

If you use the following code:

01 A PIC 9 VALUE 0.
01 B PIC S9 VALUE 0.

DISPLAY A.
ADD -2 TO A.
DISPLAY A.
ADD -4 TO A.
DISPLAY A.
ADD -6 TO A.
DISPLAY A.
DISPLAY ' '.
DISPLAY B.
ADD -2 TO B.
DISPLAY B.
ADD -4 TO B.
DISPLAY B.
ADD -6 TO B.
DISPLAY B.
DISPLAY ' '.

you get:
0
2
2
4

{
K
O
K

The second set of "answers" is due to the sign The { is a signed zero the letters are negative numbers K=-2, O=-6, etc.

rajrohith · New User Joined: 15 Apr 2005 Posts: 54 Location: chennai

what is difference between working storage copy book
and procedure division copy book
by
raj

William Thompson · Posted: Tue Dec 19, 2006 9:45 pm

raj, use a new topic when you change it..

One copys data division statements while the other copys procedure division statements.

jcbhimani · New User Joined: 30 Nov 2006 Posts: 12 Location: Ahmedabad

William what I have read is::
The operational sign is not stored as a separate character. the operational sign is stored as the zone bits of the rightmost digit position of the data item.

i.e A = +1
B = +2 ................... I = +9

J = -1
K = -2
............. R = -9

William Thompson · Posted: Tue Dec 19, 2006 10:01 pm

Yes, but since the pic did not specify the sign, when COBOL stored the result of the add back it made sure there was no sign.

If there had been a sign, what would the results been then?

jcbhimani · New User Joined: 30 Nov 2006 Posts: 12 Location: Ahmedabad

If PIC S9 was mentioned then in my opinion the answer would be:

Suppose 0 is teh initial value in a

add -2 to a ----------> a = -2 (k)

add -4 to a -----------> a = -6 (o)

add -6 to a -----------> a = -12 (internally it would be stored as k, 1 will be truncated)

What do you say William ?
Correct me if I am wrong.

William Thompson · Posted: Tue Dec 19, 2006 10:45 pm

ya got it.