CODEWITHSUNDEEP
regexcheck-digit
Jeremy
Jeremy

Reputation: 46340

mod 11 check digit with regex

Is it possible to create a mod 11 check digit routine with a regex statement?

THe nubmer is a 10 digit number,

Step 1: A = (2nd number * 2) + (3rd number * 4) + (4th number * 8) + (5th number * 5) + (6th number * 10) + (7th number * 9) + (8th number * 7) + (9th number * 3))

Step 2: B = A / 11 (ignor remainder)

Step 3: C = B * 11

Step 4: D = A - C

Step 5: 11 - D must = the 10th digit

Upvotes: 3

Views: 8921

Answers (3)

Lotus
Lotus

Reputation: 2656

Use regex as a finite state machine. http://quaxio.com/triple/

Upvotes: 5

Craig
Craig

Reputation: 12012

Regex does pattern matching, not really parsing. You need to parse the number to get the digits. I would suggest using the regex to ensure it is a 10 digit number and then ToString() it and chop it up.

Upvotes: 0

Jon Skeet
Jon Skeet

Reputation: 1500065

No - fundamentally you're wanting to do maths here, and that doesn't really fit with regular expressions which are just about patterns.

I mean, theoretically it's certainly possible - you could list all valid numbers, and combine them into one enormous regex. However, it's not practically feasible.

Upvotes: 5

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