$birthdate = ’10/12/1990′;
$currentDate = date(‘d/m/Y’);
list($birthDay, $birthMonth, $birthYear) = explode(‘/’, $birthdate);
list($currentDay, $currentMonth, $currentYear) = explode(‘/’, $currentDate);

$age = $currentYear – $birthYear;
if ($currentMonth < $birthMonth || ($currentMonth == $birthMonth && $currentDay < $birthDay)) {
return –$age;
} else {
return $age;
}