my $test = "foo bar";

print "Test is now: $test \n";
test($test);
print "Test is now: $test \n";

sub test {
	$_[0] =~ s/foo/whatever/g;
}

##</code><code>##

my @test_array = qw/foo bar test/;
print Dumper(@test_array);
test_array(\@test_array);
print Dumper(@test_array);

sub test_array {
	my $array_ref = $_[0];
	$array_ref->[1] ="whatever";
}

##</code><code>##

my %test_array;
$test_array{foo} = 1;
$test_array{bar} = 2;
$test_array{test} = 3;

print Dumper(%test_array);
test_hash(\%test_array);
print Dumper(%test_array);

sub test_hash {
	my $array_ref = $_[0];
	$array_ref->{foo} = "whatever";
}