Take 4 random values in an array with no duplicate entry

gistfile1.php

<?php

$array = array(
	'42' => 'COUCOU1',
	'87' => 'COUCOU2',
	'38' => 'COUCOU3',
	'98' => 'COUCOU4',
	'74' => 'COUCOU5',
	'16' => 'COUCOU6'
);

$copy = $array;

$random_keys = array();

while(count($random_keys) < 4)
{
	$random_key = array_rand($copy);
	$random_keys[] = $random_key;

	unset($copy[$random_key]);
}

echo '<pre>';
print_r($random_keys);
echo '</pre>';

?>