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Re: Perl Cipher & questions on semantics/layout optimisation.

by repellent (Priest)
on Feb 25, 2012 at 07:43 UTC ( #956075=note: print w/replies, xml ) Need Help??


in reply to Perl Cipher & questions on semantics/layout optimisation.

Hi, and welcome to Perlmonks! Here's my take on your code:

Find for the following line. It's in the first inner for-loop.
$offsetpattern .= chr((ord(@karray[i])+ord(@karray[i2])+ ord($offset2[ +$i % length($key)]))%256);

Notice that you have the bare variables i and i2. They ought to be $i and $i2 instead (you forgot the $). Also, the array @offset2 is not defined yet at this code point. Plus, indexing into an array should be $karray[$i] instead of @karray[$i].

Then, I notice that you call ord and chr a lot. You are joining characters only to split them later again, and that is (wasted) redundant work. In the case of the key array, you can start off by mapping the ordinals:
my @karray = map ord, (split //, $key);

That saves you the work of calling ord like ord($karray[$i2]) a whole bunch of times. This can also apply to your offset arrays. Keeping all your array elements as ordinals will make your code more concise; no need for intermediate strings.

By the way:
my @karray = map ord, (split //, $key); my $len = length($key); # prints true for both print "true" if $len == @karray; print "true" if $len-1 == $#karray;

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[Corion]: Discipulus: Well, in many cases it doesn't make sense to build an interface and complicated program just to enter 20 rows into a database ;) But yes, automating data imports should pay off in the long run
[LanX]: Choroba: this happened before I joined, was still in uni, but my boss was summoned to the CEO of the second biggest German bank at that time and could only say " I told them its not ready" ;)
[LanX]: memories....I missed my connection while chatting
[Discipulus]: in this case Corion we are speaking about software licensing: evry year or two we must rescan the whole ced to produce an excel report, while at every activation / disactivation we update a black box DB: i said that i a week i can produce the perl to..
[Discipulus]: rend out the xls IF i have access to the DB
[choroba]: LanX I miss working in a bank sometimes...
[Corion]: Discipulus: Ooof. Especially yearly things are things I like to automate instead of trying to remember how I did things last year...
[Corion]: And the second rule that I've learned is, that there is no one-off job, so writing a program for it pays off almost immediately. The third rule is to give all my programs numbers and have them reproduce that number in the name of their output files. :)
[Discipulus]: the true part is that also specification change between years.. but well our job is cheap but dont abuse of us.. ;=)

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