PHP code to work out the number of weekdays between two DateTime objects.

gistfile1.php

/**
* Weekdays between dates
*
* Works out the number of weekdays between two dates.
* @param DateTime $objStartDate The start date
* @param DateTime $objEndDate The end date
* @return int The number of weekdays or -1 if end date is before start date.
*/
function weekdaysBetweenDates(DateTime $objStartDate, DateTime $objEndDate){
	//set the time of the day to the same values since we only care about days
	$objStartDate->setTime(0, 0, 0);
	$objEndDate->setTime(0, 0, 0);
	
	//ensure the end date is not before the start date
	if($objStartDate<=$objEndDate){
		$numDays = 0;
		while($objStartDate<$objEndDate){
			if($objStartDate->format('N')<6){
				$numDays++;
			}
			$objStartDate->add(new DateInterval('P1D'));
		}
		return $numDays;
	}	
	return -1;
}