Calculate number of work days between 2 dates (See related posts)

<?php

    /**
	 * Calculates the number of work days between 2 given times
	 *
	 * @see get_holidays()
	 *
	 * @param date $start_date First date
	 * @param date $end_date Second date
	 * @param bool $workdays_only Whether to count only work days (eg. Mon-Fri)
	 * @param bool $skip_holidays Whether to use the get_holidays() function to skip holiday days as well
	 * @return int $workday_counter Number of workdays between the 2 dates
	 */
function date_difference($start_date, $end_date, $workdays_only = false, $skip_holidays = false){
    $start_date = strtotime($start_date);
    $end_date = strtotime($end_date);
    $seconds_in_a_day = 86400;
    $sunday_val = "0";
    $saturday_val = "6";
    $workday_counter = 0;
    $holiday_array = array();

    $ptr_year = intval(date("Y", $start_date));
    $holiday_array[$ptr_year] = get_holidays(date("Y", $start_date));

    for($day_val = $start_date; $day_val <= $end_date; $day_val+=$seconds_in_a_day){
        $pointer_day = date("w", $day_val);
        if($workdays_only == true){
            if(($pointer_day != $sunday_val) AND ($pointer_day != $saturday_val)){
                if($skip_holidays == true){
                    if(intval(date("Y", $day_val))!=$ptr_year){
                        $ptr_year = intval(date("Y", $day_val));
                        $holiday_array[$ptr_year] = get_holidays(date("Y", $day_val));
                    }
                    if(!in_array($day_val, $holiday_array[date("Y", $day_val)])){
                        $workday_counter++;
                    }
                }else{
                    $workday_counter++;
                }
            }
        }else{
            if($skip_holidays == true){
                if(intval(date("Y", $day_val))!=$ptr_year){
                    $ptr_year = intval(date("Y", $day_val));
                    $holiday_array[$ptr_year] = get_holidays(date("Y", $day_val));
                }
                if(!in_array($day_val, $holiday_array[date("Y", $day_val)])){
                    $workday_counter++;
                }
            }else{
                $workday_counter++;
            }
        }
    }
    return $workday_counter;
}

    /**
	 * Takes a date in yyyy-mm-dd format and returns a PHP timestamp
	 *
	 * @param string $MySqlDate
	 * @return unknown
	 */
function get_timestamp($MySqlDate){

    $date_array = explode("-",$MySqlDate); // split the array

    $var_year = $date_array[0];
    $var_month = $date_array[1];
    $var_day = $date_array[2];

    $var_timestamp = mktime(0,0,0,$var_month,$var_day,$var_year);
    return($var_timestamp); // return it to the user
}

    /**
	 * Returns the date of the $ord $day of the $month.
	 * For example ordinal_day(3, 'Sun', 5, 2001) returns the
     * date of the 3rd Sunday of May (ie. Mother's Day).
     *
     * @author  heymeadows@yahoo.com
	 *
	 * @param int $ord
	 * @param string $day (must be 3 char abbrev, per date("D);)
	 * @param int $month
	 * @param int $year
	 * @return unknown
	 */
function ordinal_day($ord, $day, $month, $year) {

    $firstOfMonth = get_timestamp("$year-$month-01");
    $lastOfMonth  = $firstOfMonth + date("t", $firstOfMonth) * 86400;
    $dayOccurs = 0;

    for ($i = $firstOfMonth; $i < $lastOfMonth ; $i += 86400){
        if (date("D", $i) == $day){
            $dayOccurs++;
            if ($dayOccurs == $ord){
                $ordDay = $i;
            }
        }
    }
    return $ordDay;
}

function memorial_day($inc_year){
    for($date_stepper = intval(date("t", strtotime("$inc_year-05-01"))); $date_stepper >= 1; $date_stepper--){
        if(date("l", strtotime("$inc_year-05-$date_stepper"))=="Monday"){
            return strtotime("$inc_year-05-$date_stepper");
            break;
        }
    }
}


    /**
	 * Looks through a lists of defined holidays and tells you which
	 * one is coming up next.
	 *
	 * @author heymeadows@yahoo.com
	 *
	 * @param int $inc_year The year we are looking for holidays in
	 * @return array
	 */
function get_holidays($inc_year){
    //$year = date("Y");
    $year = $inc_year;

    $holidays[] = new Holiday("New Year's Day", get_timestamp("$year-1-1"));
    $holidays[] = new Holiday("Australia Day", get_timestamp("$year-1-26"));
    $holidays[] = new Holiday("Labour Day", ordinal_day(1, 'Mon', 3, $year));
    $holidays[] = new Holiday("Anzac Day", get_timestamp("$year-4-25"));
    //$holidays[] = new Holiday("St. Patrick's Day", get_timestamp("$year-3-17"));
    // TODO: $holidays[] = new Holiday("Good Friday", easter_date($year));
    $holidays[] = new Holiday("Easter", easter_date($year));
    // TODO: $holidays[] = new Holiday("Easter Monday", easter_date($year));
    $holidays[] = new Holiday("Foundation Day", ordinal_day(1, 'Mon', 6, $year));
    $holidays[] = new Holiday("Queen's Birthday", ordinal_day(1, 'Mon', 10, $year));
    //$holidays[] = new Holiday("Memorial Day", memorial_day($year));
    //$holidays[] = new Holiday("Mother's Day", ordinal_day(2, 'Sun', 5, $year));
    //$holidays[] = new Holiday("Father's Day", ordinal_day(3, 'Sun', 6, $year));
    //$holidays[] = new Holiday("Independence Day", get_timestamp("$year-7-4"));
    //$holidays[] = new Holiday("Labor Day", ordinal_day(1, 'Mon', 9, $year));
    $holidays[] = new Holiday("Christmas", get_timestamp("$year-12-25"));
    $holidays[] = new Holiday("Boxing Day", get_timestamp("$year-12-26"));

    $numHolidays = count($holidays) - 1;
    $out_array = array();

    for ($i = 0; $i < $numHolidays; $i++){
        $out_array[] = $holidays[$i]->date;
    }
    unset($holidays);
    return $out_array;
}

class Holiday{
    //var $name;
    //var $date;
    public $name;
    public $date;

    // Contructor to define the details of each holiday as it is created.
    function holiday($name, $date){
        $this->name   = $name;   // Official name of holiday
        $this->date   = $date;   // UNIX timestamp of date
    }
}

?>