my $p = \@a;

##</code><code>##

my $p = [@a];

##</code><code>##

my @p = @a;

##</code><code>##

use strict;
use warnings;
use Data::Dumper;

my @a       = (1,2,3,4);
my @copy    = @a;
my $ref     = \@a;
my $refcopy = [@a];

@a = ();

print "orginal: ",    Dumper \@a;
print "array copy: ", Dumper \@copy;
print "reference: ",  Dumper $ref;
print "ref copy: ",   Dumper $refcopy;

##</code><code>##

foreach (@{$p}) { print "element $_\n"; }

##</code><code>##

print "element $_\n" for @$p;