sub pass_var {
        my ($foo,$bar) = @_;

        print "foo: $foo bar: $bar\n";
        $foo = 'c1';
        $bar = 'c2';

        print "changed: foo: $foo bar: $bar\n";
}
        

sub pass_ref {
        my ($hash) = @_;

        print "hash: $hash->{'key'}\n";

        $hash->{'key'} = 'c1';

        print "changed: hash: $hash->{'key'}\n";
        print "hashref is: $hash\n";
}

my $hash;
my $foo;
my $bar;


$foo = 1;
$bar = 2;

$hash = {'key' => 1 };

&pass_var($foo,$bar);
print "after: foo: $foo bar: $bar\n";

&pass_ref($hash);
print "after: hash: $hash->{'key'}\n";

print "hashref is: $hash\n";

##</code><code>##

foo: 1 bar: 2
changed: foo: c1 bar: c2
after: foo: 1 bar: 2
hash: 1
changed: hash: c1
hashref is: HASH(0x80f86e0)
after: hash: c1
hashref is: HASH(0x80f86e0)