ISBN-13 check digit

bbharathiraj · New User Joined: 26 Oct 2006 Posts: 50 Location: Chennai

Could some one help me to provide the COBOL code for the below logic?

The calculation of an ISBN-13 check digit begins with the first 12 digits of the thirteen-digit ISBN (thus excluding the check digit itself). Each digit, from left to right, is alternately multiplied by 1 or 3, then those products are summed modulo 10 to give a value ranging from 0 to 9. Subtracted from 10, that leaves a result from 1 to 10. A zero (0) replaces a ten (10), so, in all cases, a single check digit results.

For example, the ISBN-13 check digit of 978-0-306-40615-? is calculated as follows:

s = 9×1 + 7×3 + 8×1 + 0×3 + 3×1 + 0×3 + 6×1 + 4×3 + 0×1 + 6×3 + 1×1 + 5×3
= 9 + 21 + 8 + 0 + 3 + 0 + 6 + 12 + 0 + 18 + 1 + 15
= 93
93 / 10 = 9 remainder 3
10 – 3
= 7

Thus, the check digit is 7, and the complete sequence is ISBN 978-0-306-40615-7.

Manuneedhi K · Posted: Wed Jun 04, 2008 9:42 pm

Try this.

CICS Guy · Posted: Wed Jun 04, 2008 10:34 pm

How about?

Antonio Barata · Posted: Wed Jun 04, 2008 11:12 pm

CICS Guy

I think there is something wrong with your code.
Did you compile it?

CICS Guy · Posted: Wed Jun 04, 2008 11:17 pm

Antonio Barata · Posted: Wed Jun 04, 2008 11:24 pm

[quote=Could be, no compiler, what do you see as an error?[/quote]
The message is the following:

IGYPA3074-S "N (ALPHANUMERIC REFERENCE MODIFIED ITEM)" was not numeric, but was sender in an arithmetic expression. The statement was discarded.

It refers to the COMPUTE statement where you pick up each digit an multiply it.

CICS Guy · Posted: Wed Jun 04, 2008 11:46 pm

Ah yes, getting too cocky for my own good...Thought it would keep the usage it came from, but no.....
data-name-1(leftmost-character-position:length)
If data-name-1 is described as numeric, numeric-edited, alphabetic, or alphanumeric-edited, it is operated upon for purposes of reference modification as if it were redefined as an alphanumeric data item of the same size as the data item referenced by data-name-1.

Antonio Barata · Posted: Thu Jun 05, 2008 12:00 am

I think this code will do the job, providing that you put all the numbers in the numeric field "ws-array":

WORKING-STORAGE SECTION.
01 ws-ind PIC S9(4) COMP VALUE 0.
01 ws-multiplier-factor PIC S9(3) COMP-3 VALUE 0.
01 ws-sum PIC S9(5) COMP-3 VALUE 0.
01 ws-ckd PIC 9(02) VALUE 0.

01 ws-array PIC 9(13) VALUE 1234567890321.
01 FILLER REDEFINES ws-array.
02 ws-number OCCURS 13 PIC 9.

PROCEDURE DIVISION.
0000-MAIN.
PERFORM VARYING ws-ind FROM 1 BY 1
UNTIL ws-ind > LENGTH OF ws-array
IF FUNCTION REM(ws-ind 2) = 1
MOVE 1 TO ws-multiplier-factor
ELSE
MOVE 3 TO ws-multiplier-factor
END-IF
COMPUTE ws-sum = ws-sum
+ ( ws-number(ws-ind)
* ws-multiplier-factor )
END-PERFORM.
COMPUTE ws-ckd = 10 - FUNCTION MOD(ws-sum 10)
DISPLAY ws-ckd.

I compiled it Ok. Didn't test it. Please do.

bbharathiraj · New User Joined: 26 Oct 2006 Posts: 50 Location: Chennai

Thanks to every one. All your codes are working fine.