Greetings all.

So, I'm relatively new to Perl, and I've managed to screw up a Perl task that should be quite trivial. I have two files - one of ~16k records and another of ~240k records. I want to extract a string from each line of the first file(16k records), and subsequently check each record of the second file(~240k records) for a matching string. My take on it is below. Seems like it should work, but a couple of notes:

1. It doesn't work. My logic seems correct to me, but no match is found using an array of ids extracted from the 16k record file when looped against every element of the 240k record file. There should be ~16k matches. If I hard code one of the values from the array, a match is indeed found.

2. Even if it was working, it is no doubt horribly inefficient. I suspect I should use hashes somehow here, but I don't understand enough about those structures to implement them in this case.

So if anyone can shed some light as to where I have dropped the ball, I would really appreciate it. Any tips on how to make this script more efficient using hashes would be greatly appreciated as well. Style critique is appreciated also. Thanks!

#!/usr/bin/perl

use strict;
use warnings;

open (PIDS, $ARGV[0]);
open (FIDS, $ARGV[1]);
open (OUTPUT, ">$ARGV[2]");

my @pids = <PIDS>;
my @fids = <FIDS>;
my @pidCans;
my @fidCans;
my $result;
my $pidCan;
my $fid;
my $pid;

foreach $pid (@pids) {

   $result = '';
   $pid =~ /\|(.*)$/;
   $result = $1;
   push (@pidCans, $result);
}


foreach $pidCan (@pidCans)  {

  chomp $pidCan;

    foreach $fid (@fids)  {
      chomp $fid;
      print "Comparing $fid to $pidCan" . "\n";
         if ($fid =~ /$pidCan/) {
         print "FOUND A MATCH.\n";
         print OUTPUT $fid . "\n";
         }
   }
}

close PIDS;
close FIDS;
close OUTPUT;

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In reply to My code sucks, please help me understand why. by mirage4d

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