#!/usr/bin/perl -w
use strict;
use Carp;
use Data::Dumper;

sub array_ref
{
    my $array_ref = shift;
    croak 'Not an array reference' unless ref($array_ref) eq 'ARRAY';

    print Dumper($array_ref);
}

my @array = qw/ 1 2 3 4 5 /;
my %hash = qw/ 1 1 2 2 3 3 4 4 5 5 /;

array_ref(\@array);
array_ref(\%hash);