Swat/SwatDate.php
public function addDays($days)
    {
        $days = (int) $days;
        $interval = new DateInterval('P' . abs($days) . 'D');

        if ($days < 0) {
            $interval->invert = 1;
        }

        return $this->add($interval);
    }
public function addDays($days)
    {
        $days = (int) $days;
        $interval = new DateInterval('P' . abs($days) . 'D');

        if ($days < 0) {
            $interval->invert = 1;
        }

        return $this->add($interval);
    }
public function addDays ( $ days ) { $ days = ( int ) $ days ; $ interval = new DateInterval ( 'P' . abs ( $ days ) . 'D' ) ; if ( $ days < 0 ) { $ interval -> invert = 1 ; } return $ this -> add ( $ interval ) ; }
Adds the specified number of days to this date

@param integer $days the number of days to add.

@return this object on success or false on failure.
Adds the specified number of days to this date