I want to pass by reference so I have no chance of harming my origional data.

I think you're a little confused about what passing-by-reference entails. You can easily take a reference to a reference -- you were correct about how to do that ( \$arrayRef ). If $refref is a reference to a reference to an array, then you can get the original array with @$$refref. But this does nothing to protect your original data. You're just going through an extra dereferencing step. If you want to make a copy of your original data, do a super-search for "deep copy." There are lots of methods depending on your needs.

This will pass a reference to a new copy of the original reference's data ("sub" is a really bad name for a sub, so I'll call it "stub"):

stub([@{$arrayRef}]);
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stub([map {[@$_]} @$arrayRef]);
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stub([map {{%$_}} @$arrayRef]);
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Can you guys reccomend any good books that go indepth on references?

perlreftut, and perllol, should get you started.

"Learning Perl Objects, References & Modules", O'Reilly Publ.
chas

In your case, if someone says passing by reference, it usually means:

foo($arrayRef);
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As $arrayRef is a reference already. In the same sense, if you have @array, then you:

foo(\@array);
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If you don't want to pass by reference, you just:

foo(@array);
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Maybe offtopic but keep in mind that when passing more than one parameter the parameter list will be flattened. You do need references in that case to distinguish between the items in your parameter list!

The following code doesn't consider the two different arrays, it only sees one long parameter list.

#! /usr/bin/perl
use strict;
use warnings;

my @array1 = ( 1, 2, 3, 4, 5);
my @array2 = ( 1, 2, 3, 4, 5);

list(@array1,@array2);

sub list { 
    foreach my $c (@_) {
        print $c . " ";
    }
}
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The following code only expects references and will treat each reference as an array reference.

#! /usr/bin/perl
use strict;
use warnings;

my @array1 = ( 1, 2, 3, 4, 5);
my @array2 = ( 1, 2, 3, 4, 5);

list(\@array1,\@array2);

sub list { 
    foreach my $r (@_) {
        foreach my $c (@$r) {
            print $c . " ";
        }
        print "\n";
    }
}
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--
if ( 1 ) { $postman->ring() for (1..2); }

This node has a good discussion on 'deep' copies.
Pass by value acts like pass by reference

Edited by planetscape - minor formatting; fixed internal link

intro to references and References quick reference and must-read and must-bookmark nodes. :-)

HTH,