PHP get number of week for month

Edit: so much for "single line" - needed variables to avoid recomputation with the conditional. Tossed in a default argument while I was at it.

function weekOfMonth($when = null) {
    if ($when === null) $when = time();
    $week = date('W', $when); // note that ISO weeks start on Monday
    $firstWeekOfMonth = date('W', strtotime(date('Y-m-01', $when)));
    return 1 + ($week < $firstWeekOfMonth ? $week : $week - $firstWeekOfMonth);
}

Please note that weekOfMonth(strtotime('Oct 31, 2011')); will return 6; some rare months have 6 weeks in them, contrary to OP's expectation. January 2017 is another month with 6 ISO weeks - Sunday the 1st falls in the last year's week, since ISO weeks start on Monday.

For starshine531, to return a 0 indexed week of the month, change the return 1 + to return 0 + or return (int).

For Justin Stayton, for weeks starting on Sunday instead of Monday I would use strftime('%U' instead of date('W', as follows:

function weekOfMonth($when = null) {
    if ($when === null) $when = time();
    $week = strftime('%U', $when); // weeks start on Sunday
    $firstWeekOfMonth = strftime('%U', strtotime(date('Y-m-01', $when)));
    return 1 + ($week < $firstWeekOfMonth ? $week : $week - $firstWeekOfMonth);
}

For this version, 2017-04-30 is now in week 6 of April, while 2017-01-31 is now in week 5.

public function getWeeks($timestamp)
{
    $maxday    = date("t",$timestamp);
    $thismonth = getdate($timestamp);
    $timeStamp = mktime(0,0,0,$thismonth['mon'],1,$thismonth['year']);    //Create time stamp of the first day from the give date.
    $startday  = date('w',$timeStamp);    //get first day of the given month
    $day = $thismonth['mday'];
    $weeks = 0;
    $week_num = 0;

    for ($i=0; $i<($maxday+$startday); $i++) {
        if(($i % 7) == 0){
            $weeks++;
        }
        if($day == ($i - $startday + 1)){
            $week_num = $weeks;
        }
      }     
    return $week_num;
}

Hello all i have been struggling for the whole day trying to figure this code out, i finally figured it out so i thought i would share it with you all.

all you need to do is put a time stamp into the function and it will return the week number back to you.

thanks

The most frustrating thing I have ever tried to get working - but here it is!

<?php

    /**
     * Returns the amount of weeks into the month a date is
     * @param $date a YYYY-MM-DD formatted date
     * @param $rollover The day on which the week rolls over
     */
    function getWeeks($date, $rollover)
    {
        $cut = substr($date, 0, 8);
        $daylen = 86400;

        $timestamp = strtotime($date);
        $first = strtotime($cut . "00");
        $elapsed = ($timestamp - $first) / $daylen;

        $weeks = 1;

        for ($i = 1; $i <= $elapsed; $i++)
        {
            $dayfind = $cut . (strlen($i) < 2 ? '0' . $i : $i);
            $daytimestamp = strtotime($dayfind);

            $day = strtolower(date("l", $daytimestamp));

            if($day == strtolower($rollover))  $weeks ++;
        }

        return $weeks;
    }


    //
    echo getWeeks("2011-06-11", "sunday"); //outputs 2, for the second week of the month
?>