An age calculation function accurate to days written in PHP

/**
* PHP age calculation function
*
* Parameters support array parameter passing and standard Mysql date type parameter passing
* params sample
* ------------------
$birthArr = array(
'year' => '2000',
'month' => '11',
'day' => '3'
);
$birthStr = '2000-11-03';
 * ------------------
* );
* @author
* @copyright (c) 2011,2012 Just Use It!
* @link IT tumbler http:/ /yungbo.com http://bbs.it-home.org
* @param string|array $birthday
* @return number $age
*/
function getAge($birthday) {
  $age = 0;
  $year = $month = $day = 0;
  if (is_array($birthday)) {
     extract($birthday);
  } else {
     if (strpos($birthday, '-') !== false) {
     list($year, $month, $day) = explode('-', $birthday);
     $day = substr($day, 0, 2); //get the first two chars in case of '2000-11-03 12:12:00'
}
}
$age = date('Y') - $year;
if (date('m') < $month || (date('m') == $month && date('d') < $day)) $age--;
return $age;
}
?>