PHP - Common Date and Time functions

commonDateTimeFunctions.php

<?php 
class Common_Datetime {

static public function months() {
        $month_name_arr = array("January", "February", "March", "April", "May", "June", "July", "August", "September", "October", "November", "December");
        $month_name_arr = array("january", "february", "march", "april", "may", "june", "july", "august", "september", "october", "november", "december");
        return $month_name_arr;
    }

/**
     * return week start and end dates
     * 
     * Please note that the first Monday of the year is not not necessarily the same thing as the Monday of ISO week 1. 
     * Week 1 is deemed to be the week that holds the first Thurday of a year. 
     * So, for example week 1 of 2013 will begin on 31/12/2013. 
     *   en.wikipedia.org/wiki/ISO_week_date#First_week 
     * @param type $year
     * @return array
     */
    static public function week_starting_dates($year) {

        $firstDayOfYear = mktime(0, 0, 0, 1, 1, $year);
        $thursday = strtotime('thursday', $firstDayOfYear);
        
        while (date('Y', $thursday) == $year) {
            
            $monday = strtotime('previous monday', $thursday);
            $sunday = strtotime('next sunday', $monday);
            $week_starting_dates_arr[] = array(
                'start'=> date('d/m',$monday),
                'end' => date('d/m',$sunday));
            //increment
            $thursday = strtotime('+1 week',$thursday);
           
        }

        //Zend_Debug::dump($week_starting_dates_arr);exit;
        
        return $week_starting_dates_arr;
    }

    static function weeknumber($date){

        
        $ts = strtotime($date);
        $weeknumber = (int)date('W', $ts);
        
        return $weeknumber;
        
    }

public function dateRange($first, $last, $step = '+1 day', $format = 'Y-m-d' ) { 

        $dates = array();
        $current = strtotime($first);
        $last = strtotime($last);

        while( $current <= $last ) { 

            $dates[] = date($format, $current);
            $current = strtotime($step, $current);
        }

        return $dates;
    }

static function week_range($date) {

        $ts = strtotime($date);
        $wd = date('w', $ts);
        
        if ($wd == 1) {
            $start = strtotime('today', $ts);
        } else {
            $start = strtotime('last monday', $ts);
        }

        $week_start_end = array(
            date('Y-m-d', $start),
            date('Y-m-d', strtotime('next tuesday', $start)),
            date('Y-m-d', strtotime('next wednesday', $start)),
            date('Y-m-d', strtotime('next thursday', $start)),
            date('Y-m-d', strtotime('next friday', $start)),
            date('Y-m-d', strtotime('next saturday', $start)),
            date('Y-m-d', strtotime('next sunday', $start)))
        ;

        return $week_start_end;
    }

static function weekDayName($date) {
        $week = Common_Datetime::week_range($date);
        $key = array_search($date, $week);
        $daynames = array('monday', 'tuesday', 'wednesday', 'thursday', 'friday', 'saturday', 'sunday');
        $weekday = $daynames[$key];
        return $weekday;
    }


}