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Re^3: Explain the code

by gopalr (Priest)
on Jul 24, 2008 at 13:08 UTC ( #699868=note: print w/replies, xml ) Need Help??

in reply to Re^2: Explain the code
in thread Explain the code

How? If the array (@a) has duplicate values, hash will eliminate that.

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Re^4: Explain the code
by olus (Curate) on Jul 24, 2008 at 13:12 UTC

    Noticed the ++ in !$seen{$_}++?

    perl -MData::Dumper -e '@a=(1, 2, 1, 2, 3); my @result = grep { !$seen +{$_}++ } @a; print Dumper(\%seen);' $VAR1 = { '1' => 2, '3' => 1, '2' => 2 };
Re^4: Explain the code
by moritz (Cardinal) on Jul 24, 2008 at 13:09 UTC
    The ++ is evaluated for every item in @a, grep only checks its return value and picks (or not picks) the element based on that value.
Re^4: Explain the code
by FunkyMonk (Canon) on Jul 24, 2008 at 13:11 UTC
    $seen{4} = 3 means that 4 has been seen 3 times.

    Unless I state otherwise, all my code runs with strict and warnings

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[stevieb]: I'm working on it to fatten it up and make it more reliant so I can finalize my Raspberry Pi automated build system for that software :) It's all well and fun, until I try to make it work with Windows lol
[shmem]: "debugging a program is more difficult than to write it in the first place. If you code your program as smart as you are, you are, by definition, too dumb to debug it."
[stevieb]: I literally laughed. That's good :) Perhaps I just need to go climb another mountain and forget about it
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