reference \@

\@skipper, the result is a reference to that array. A reference to the array is like a pointer: it points at the array, but it is not the array itself.

A reference fits wherever a scalar fits. It can go into an element of an array or a hash, or into a plain scalar variable, like this:

my $reference_to_skipper = \@skipper;

Because we can copy a reference, and passing an argument to a subroutine is really just copying, we can use this code to pass a reference to the array into the subroutine:

my @skipper = qw(blue_shirt hat jacket preserver sunscreen);
check_required_items("The Skipper", \@skipper);

sub check_required_items { my $who = shift; my $items = shift; my @required = qw(preserver sunscreen water_bottle jacket); for my $item (@required) { unless (grep $item eq $_, @{$items}) { # not found in list? print "$who is missing $item.\n"; } } }

in the above case, the dereference array can be written like @$items.

Now $items in the subroutine is a reference to the array of @skipper.

Dereferencing the Array Reference

That is, wherever we write skipper to name the array, we use the reference inside curly braces: { $items }. For example, both of these lines refer to the entire array:

@ skipper @{ $items } #the $items is a reference to array.

whereas both of these refer to the second item of the array:
$ skipper [1] ${ $items }[1]

#!/usr/bin/perl -w
#
use strict;

my @skipper = qw(blue_shirt hat jacket preserver sunscreen);
check_required_items('The Skipper', \@skipper);

sub check_required_items{
#my $who = shift;
#    my $items = shift;
    my @required = qw(preserver sunscreen water_bottle jacket);

    foreach my $item (@required){
        unless( grep $item eq $_, @{$_[1]}){
            print "$_[0] missing $item\n";
        }
    }
}