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Re^4: why can't I just cat the file???

by halley (Prior)
on Feb 08, 2008 at 18:04 UTC ( #667030=note: print w/replies, xml ) Need Help??


in reply to Re^3: why can't I just cat the file???
in thread why can't I just cat the file???

I agree it's one of those cases where Perl's magic is hard to document, since it's only found when you combine TWO features (looping and inputting), not just one (inputting or looping).

There's a tiny mention of it in perlvar, but the real money is in perlop under the "I/O Operators."

My favorite is to simply ask Perl what is going on under the covers with the B::Deparse module. The deparse module will then show you the loop that Perl wrote for you!

$ perl -MO=Deparse -e"while(<>){'???'}" ------------------------------------ LINE: while (defined($_ = <ARGV>)) { '???'; }
For kicks, you can deparse the script which Perl writes for you, when you use command options like -p or -n.
$ perl -MO=Deparse -p -e"???" ------------------------------------ LINE: while (defined($_ = <ARGV>)) { '???'; } continue { print $_; }

--
[ e d @ h a l l e y . c c ]

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[Cosmic37]: greetings earthlings please can someone improve my pathetic perl knowledge
[Cosmic37]: I have 2 files each with datetime and other data in unknown order and I want to find rows from both files matching by datetime and output them combined/ concatenated
[Corion]: Sure
[Corion]: Do you have any specific interests or general Perl knowledge?

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