function daysBetweenDates($dateStart,$dateEnd) {
        // dateStart and dateEnd in the form of 'YYYY-MM-DD'
        $dateStartArray = explode("-",$dateStart);
        $dateEndArray = explode("-",$dateEnd);
       
        $startYear = $dateStartArray[0];
        $startMonth = $dateStartArray[1];
        $startDay = $dateStartArray[2];
       
        $endYear = $dateEndArray[0];
        $endMonth = $dateEndArray[1];
        $endDay = $dateEndArray[2];
       
        //first convert to unix timestamp
        $init_date = mktime(12,0,0,$startMonth,$startDay,$startYear);
        $dest_date = mktime(12,0,0,$endMonth,$endDay,$endYear);

        $offset = $dest_date-$init_date;

        $days = floor($offset/60/60/24);
        return $days;
}