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Perl script to mask a credit card number

Here's the basic idea: given a 16 digit credit card number, I want to replace the first 12 digits with x's.

Example: 1223 1223 1234 2345 would become xxxx xxxx xxxx 2345

I'm using ActiveState Perl.

Thanks for any assistance!

ASKER CERTIFIED SOLUTION

jmcg

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EschbacherG

ASKER

What if there are no spaces in the cardnumber?

like 123412324123241234? Can i just remove your spaces from your regular expression?

SOLUTION

ahoffmann

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jmcg

If preserving the spaces (or lack of spaces) is important, you'll have to do something more like what ahoffman is showing you. If you want the x-ed-out credit card number to look a particular way, however, you're better off using my approach.

josephfluckiger

Hope you don't mind me asking a question here, but what does the "e" at the end of the expression do?

$credit_card_number=~s((\d{4}( ?)){3})((x x 4) x 3)e; <----

jmcg

An "e" modifier on a substitution indicates that the right hand side of the substitution is to be interpreted as a perl expression rather than as a double-quoted string literal (well, nearly). You can even put extra "e"s there to get multiple levels of expression interpretation, but I've never seen this usefully done more than two levels deep.

josephfluckiger

thanks, I owe you some points :).

sorry to use your question space EschbacherG.

ahoffmann

well, my suggestion is not perfect, and to be improved in many ways (as jmcg's too:), but it answers the question
KISS - keep it stupid simple ;-)

josephfluckiger, probably you replace
x x 4
in my suggestion by
X x 4
to understand what happens
print "X" x 4
characters are just characters, and some have special meaning in special context ..

EschbacherG

ASKER

Thank you both very much for your quick answers. In the end, I went with jmcg's suggestion.

joneoytk

so what if the input from keyboard and i dont want it to show on the screen.does this command (my $credit_card_number_masked = $credit_card_number) =~ s/.*(\d{4})$/xxxx xxxx xxxx $1/;
work on my concept too?