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check digit ?

Hi,

I need to check wether an Isin code specified by a user is valid or not..
I found this article exaplaining an algoryhtm to compute a "check digit" : http://en.wikipedia.org/wiki/International_Securities_Identifying_Number
But what do I have to do after calculating this check digit ?

Maybe if you have some experience in security, you understand what this is about ? (I have none)

Thank you.

ASKER CERTIFIED SOLUTION

Chris Bottomley

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matthew016

ASKER

I am not sure I understand.
If user makes a typo, I will compute a certain digit. How can I detect from this digit that he made a typo ?

Chris Bottomley

Error checking is a speciality in it's own right ... i'm not saying i'm an expert but as far as I can see the referenced syntax will indicate an error exists but it is not error correcting and will not indicate which character, (or characters are wrong).

i.e. when requesting or receiving the data you should calculate the check digit for each datum and ensure it is correct before proceeding and where any individual datum is wrong reject it and move on.

Chris

matthew016

ASKER

Well I need to know how I detect an error exists.
I do not want to correct the error.

But now I am maybe confusing
* error detection in some kind of I/O operations, etc. and
* validation to check if the data entered is a valid sequence

matthew016

ASKER

nevermind ...

I see that I can check the digit computed with the last number of the sequence number.