$start_time = time(); // 当前时间
$end_time = time(); // 结束时间
if($end_time <= $start_time) return '结束时间不能小于开始时间';
$start_date = date('Y-m-d', $start_time);
$end_date = date('Y-m-d', $end_time );
$datetime_start = new \DateTime($start_date);
$datetime_end = new \DateTime($end_date);
$lease_day = $datetime_start->diff($datetime_end)->days; // 得出天数