Modulus 10

[ErnstNoto]

Hi!
I need to calculate modulus 10 in a crystal reports

I know how to calculate this manually but I have a bit of a problem figuring out how to calculate the check digit and create the new number in crystal reports.

Anyone who can help?

Best Regards
Ernst

Best Regards
Ernst Noto

 

[briangriffin]

This seems to work, but please test thoroughly:

whileprintingrecords;
stringvar v_cc;
stringvar v_temp;
numbervar v_calc;
numbervar v_result;
numbervar v_counter;

v_cc := replace({YourCCfield}," ","");

// Double every other digit starting with the next to last digit.

numbervar v_counter := len(v_cc) - 1;

while v_counter > 0

do
(v_temp := mid(v_cc,v_counter,1);
v_calc := tonumber(v_temp) * 2;

if v_calc >= 10 then v_calc := tonumber(left(totext(v_calc,"#",0),1))+ tonumber(right(totext(v_calc,"#",0),1))
else
v_calc;

v_result := v_result + v_calc;
v_counter := v_counter - 2);

// Add in the non-doubled digits
v_counter := len(v_cc);

while v_counter > 0

do
(v_temp := mid(v_cc,v_counter,1);
v_calc := tonumber(v_temp);
if v_calc >= 10 then v_calc := tonumber(left(totext(v_calc,"#",0),1)) + tonumber(right(totext(v_calc,"#",0),1))
else
v_calc;

v_result := v_result + v_calc;
v_counter := v_counter - 2);

// Calculate check digit
v_result mod 10

 

[ErnstNoto]

Thank you!
This I would not have figured out, thank you. I think we're on the right track. I have tried it and the formula works and does calculate a digit, but it is not the correct one.

Ex: I have this number: 2238310098314000000
The check digit with moudulus10 should be 1 and my new number (CID) should then become: 22383100983140000001

But when using your formula, it returns the digit 6 and the new number then becomes 22383100983140000006

In your formula you have noted the following: // Double every other digit starting with the next to last digit.

But should you not start doubling the last digit and not the next to last? I am however not sure if this is the only thing, I cant say cause I dont know if I understand the formula.

Best Regards
Ernst

Best Regards
Ernst Noto

 

[briangriffin]

It seemed like there was conflicting information on how to do this on the sites I looked at.

Please describe your method for calculating this manually and we can adjust the formula accordingly.

 

[ErnstNoto]

Great!

I have used this method, and it seems to be correct according to a control program i have.

http://en.m.wikipedia.org/wiki/Luhn_algorithm

Best regards
Ernst

Best Regards
Ernst Noto

 

[briangriffin]

OK, this works better:

whileprintingrecords;
stringvar v_cc;
stringvar v_temp;
numbervar v_calc;
numbervar v_result;
numbervar v_counter;

v_cc := replace({YourDBField}," ","");

// Double every other digit starting with the last digit.

numbervar v_counter := len(v_cc);

while v_counter > 0

do
(v_temp := mid(v_cc,v_counter,1);
v_calc := tonumber(v_temp) * 2;

if v_calc >= 10 then v_calc := tonumber(left(totext(v_calc,"#",0),1))+ tonumber(right(totext(v_calc,"#",0),1))
else
v_calc;

v_result := v_result + v_calc;
v_counter := v_counter - 2);

// Add in the non-doubled digits
v_counter := len(v_cc) - 1;

while v_counter > 0

do
(v_temp := mid(v_cc,v_counter,1);
v_calc := tonumber(v_temp);
if v_calc >= 10 then v_calc := tonumber(left(totext(v_calc,"#",0),1)) + tonumber(right(totext(v_calc,"#",0),1))
else
v_calc;

v_result := v_result + v_calc;
v_counter := v_counter - 2);

// Calculate check digit
v_cc + right(totext(v_result * 9,"#",0),1)

 

[ErnstNoto]

Hi!
Thank you again, but I am afraid it still isnt correct. That is, I find that the first number the report encounters, is alway correct, and the rest is always wrong.

I dont know what happens, but the formula does not seem to reset when it is going to calculate the next number it encounter. If I only show one number it is correct and otherwise, only the first number.

Best Regard
Ernst





Best Regards
Ernst Noto

 

[briangriffin]

Sorry, I was only testing one number at a time.

Change the variable declarations at the beginning of the formula to reset for every record:

whileprintingrecords;
stringvar v_cc := "";
stringvar v_temp := "";
numbervar v_calc := 0;
numbervar v_result := 0;
numbervar v_counter := 0;

That should do the trick.

 

[ErnstNoto]

Brilliant!

Thank you

Best Regards
Ernst

Best Regards
Ernst Noto