I had to use un function which finds every elements in an array. So I modified the function done by Jakub Trunecek as follow:
function search_in_array_r($needle, $array) {
$found = array();
foreach ($array as $key => $val) {
if ($val[1] == $needle) {
array_push($found, $val[1]);
}
}
if (count($found) != 0)
return $found;
else
return null;
}