Work out the days between two dates using PHP

I've popped this up as I needed to work out the number of dates in between two dates. Again something similar might be out there, but I thought it may be useful for any one out there that may need it.

Parameters

Required - date1 and date2: Dates in the following format yyyy-mm-dd
Optional - inclusive: If you set to true it includes the two provided dates in it's calculation
Optional - return format of the dates: Combination of PHP's date formatting options

Return Values

Returns an array of dates and the number of days

The Code

/**
    * Get the difference between two dates...
    * @param string $date1 yyyy-mm-dd
    * @param string $date2 yyyy-mm-dd
    * @param boolean $inclusive
    * @param string $return format
    *
    * @return array of total number of days and the dates in the prescribed format
*/

function days_between($date1, $date2, $inclusive = true, $return_format = 'Y-m-d') {
       
        $date_array = array();
        $output_array = array();
       
        $date1_ts = strtotime($date1);
        $date2_ts = strtotime($date2);
        $second_difference = $date2_ts-$date1_ts;
        $num_days = floor($second_difference / 86400);
     
        if (is_numeric($num_days) && $num_days > 0) {
         
            for ($i = 0; $i <= $num_days; $i++) {
                $new_day = $date1_ts + ($i*86400);
                $date_array[] = date($return_format,$new_day);
            }

            if (!$inclusive) {
                unset($date_array[0]);
                array_pop($date_array);
            }
         
            $output_array['number_of_days'] = sizeof($date_array);
            $output_array['dates_between'] = $date_array;  
         
        }

        return ($output_array);
     
}    

Usage

days_between('2011-12-31', '2012-01-05', 1,'d M Y');