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Re^2: Code Review: Simple Credit Card Number Validation

by marquezc329 (Scribe)
on Oct 01, 2012 at 02:47 UTC ( #996572=note: print w/replies, xml ) Need Help??

in reply to Re: Code Review: Simple Credit Card Number Validation
in thread Code Review: Simple Credit Card Number Validation

Thank you for your quick and thorough reply. After looking through your revision I can quickly see how my nested control structures were exaggerated nearly to the point of obnoxious. In particular I really liked your use of:
for my $i (map {$_ * 2} 0 .. $#cardNum / 2) { $cardNum[$i] *= 2; $cardNum[$i] -= 9 if $cardNum[$i] >= 10; }
to cycle through @cardNum. I had thought of trying to use map, but wasn't quite sure how to pick every other element. The only part I don't quite understand is:
return <<INFO; Card Number: $cardNum Issuer: $issuers{$iDigit} INFO
I can see that the subroutine is returning a block called INFO, but I don't quite get the syntax behind the way you defined that block. Is there a name for this style of definition that I can research for a better understanding? Thank you again for reviewing my code. I'm a bit disappointed with myself looking back, but I suppose sophisticated code comes with time and practice.

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Re^3: Code Review: Simple Credit Card Number Validation
by GrandFather (Sage) on Oct 01, 2012 at 03:11 UTC

    The <<INFO syntax is (*nix) shell like here-doc line oriented quoting. It's really handy when you have multiple lines of quoted text you want to shovel into a parameter list. You'll want to search the linked documentation for here-doc.

    True laziness is hard work

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