Zend Date - Tagesunterschied

Ich habe die folgende Codezeile $day1 = new Zend_Date('2010-03-01', 'YYYY-mm-dd'); $day2 = new Zend_Date('2010-03-05', 'YYYY-mm-dd'); $dateDiff = $day2->getDate()->get(Zend_Date::TIMESTAMP) - $day1->getDate()->get(Zend_Date::TIMESTAMP); $days = ...