I tried figuring this out and have absolutely no idea. I looked at "Mastering Algorithms with Perl" but quickly got lost in the "Searching" chapter.

There are two data structures that are returned from DBI->fetchall_arrayref

I want to compare the arrays in both structures against each other and match on a specific element in the array, in this case the third element. All the arrays that match I want to store into a new data structure

Here is as far as I got, I need help with the subroutine: 

#!/usr/bin/perl -w

use strict;
use Data::Dumper;



# Array Reference
my @array1 = ( ["a", "b", "match"], ["c", "d", "e"],
                   ["f", "g", "h"], ["i", "j", "k"], );

my @array2 = ( ["l", "m", "z"], ["n", "o", "p"],
                   ["q", "r", "s"], ["t", "u", "match"], );



#  Make data structure similar to DBI's ->fetchall_arrayref;
my $array_ref1 = \@array1;
my $array_ref2 = \@array2;



                   #  Pass in data structures and define
                   #  which element to match against.
my @matchedLists = &commonLists( \$array_ref1, \$array_ref2, 2 );

print Dumper \@matchedLists;



sub commonLists {

    my ( $array_ref1, $array_ref2, $elementToMatch ) = @_;

    #  Find the common lists where element $elementToMatch matches.
    #  Result should return both lists that have "match"
    #  in their third element.

    return \@match;
}

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In reply to How to match specific elements of multiple array_references by awohld

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