Checking Credit Cards (#122)
in [Ruby]
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From: Tim Becker on 27 Apr 2007 09:37 > > JCB 3528-2589 Length: 16 should be 3528-3589, obviously. > > Diners 3000-3029, 3040-3059, 36, 3815-3889, 389 Length: 14 > Wow, those are some broad ranges. Well, those ranges DO include Carte Blanche :) I haven't seen a physical Diners Card in at least 20 years to be honest, not sure who still uses them. If you think those ranges are broad, the last UK-Switch/Solo table I had has over 180 card prefixes with different card lengths...
From: John Joyce on 27 Apr 2007 10:15 On Apr 27, 2007, at 10:37 PM, Tim Becker wrote: >> > JCB 3528-2589 Length: 16 > > should be 3528-3589, obviously. > >> > Diners 3000-3029, 3040-3059, 36, 3815-3889, 389 Length: 14 > >> Wow, those are some broad ranges. > > Well, those ranges DO include Carte Blanche :) I haven't seen a > physical Diners Card in at least 20 years to be honest, not sure who > still uses them. > > If you think those ranges are broad, the last UK-Switch/Solo table I > had has over 180 card prefixes with different card lengths... > My grandmother used to have a Diners Club card. Last time I saw that was about 20 years ago too. But of the cards accepted here in Tokyo, Diners Club is one that is often listed! (in bars and restaurants of course) Oh, I can only imagine. Processing cards with less deeply thought out numbering schemes. The big boys planned that stuff back when computing power was a premium.
From: Matthew Moss on 27 Apr 2007 13:58 > +============+=============+===============+ > | Card Type | Begins With | Number Length | > +============+=============+===============+ > | AMEX | 34 or 37 | 15 | > +------------+-------------+---------------+ > | Discover | 6011 | 16 | > +------------+-------------+---------------+ > | MasterCard | 51-55 | 16 | > +------------+-------------+---------------+ > | Visa | 4 | 13 or 16 | > +------------+-------------+---------------+ So is a card number like "4012 3456 7890" a valid Unknown, or an invalid Visa? Similarly, for Unknown, should we accept any length, or go for the common 16?
From: James Edward Gray II on 27 Apr 2007 14:20 On Apr 27, 2007, at 12:58 PM, Matthew Moss wrote: >> +============+=============+===============+ >> | Card Type | Begins With | Number Length | >> +============+=============+===============+ >> | AMEX | 34 or 37 | 15 | >> +------------+-------------+---------------+ >> | Discover | 6011 | 16 | >> +------------+-------------+---------------+ >> | MasterCard | 51-55 | 16 | >> +------------+-------------+---------------+ >> | Visa | 4 | 13 or 16 | >> +------------+-------------+---------------+ > > So is a card number like "4012 3456 7890" a valid Unknown, or an > invalid Visa? Visa Invalid Always match the type first. > Similarly, for Unknown, should we accept any length, or go for the > common 16? Unknown is for any type that doesn't match, so it could be any length. James Edward Gray II
From: Matthew Moss on 27 Apr 2007 15:31
So I took this as an opportunity to try doing a little TDD, something which is appealing but I've never really tried. It _is_ fun to see failure first and then fix. =) There are probably other tests I could have included, but here is a start, in case people want to check a few numbers or add more tests: Obviously, you may need to change this to match your solution... require "test/unit" require "ccard" class CreditCardCheckTest < Test::Unit::TestCase def test_valid_numbers assert CreditCard.new("4408041234567893").valid? assert CreditCard.new("6011111111111117").valid? end def test_invalid_nubers assert !CreditCard.new("4417123456789112").valid? end def test_valid_numbers_with_spaces assert CreditCard.new("4408 0412 3456 7893").valid? assert CreditCard.new("6011 1111 1111 1117").valid? end def test_invalid_nubers_with_spaces assert !CreditCard.new("4417 1234 5678 9112").valid? end def test_valid_types assert_equal CreditCard.new("4408041234567893").type, :visa assert_equal CreditCard.new("4408 0412 3456 7893").type, :visa assert_equal CreditCard.new("6011 1111 1111 1117").type, :discover assert_equal CreditCard.new("123456789").type, :unknown end def test_invalid_types assert_nil CreditCard.new("4408 0412 3456 789").type end end |