hendry hendry - 18 days ago 8
PHP Question

Calculating days of week given a week number

Given a week number, e.g.

date -u +%W
, how do you calculate the days in that week starting from Monday?

Example rfc-3339 output for week 40:

2008-10-06
2008-10-07
2008-10-08
2008-10-09
2008-10-10
2008-10-11
2008-10-12

Answer

PHP

$week_number = 40;
$year = 2008;
for($day=1; $day<=7; $day++)
{
    echo date('m/d/Y', strtotime($year."W".$week_number.$day))."\n";
}


Below post was because I was an idiot who didn't read the question properly, but will get the dates in a week starting from Monday, given the date, not the week number..

In PHP, adapted from this post on the PHP date manual page:

function week_from_monday($date) {
    // Assuming $date is in format DD-MM-YYYY
    list($day, $month, $year) = explode("-", $_REQUEST["date"]);

    // Get the weekday of the given date
    $wkday = date('l',mktime('0','0','0', $month, $day, $year));

    switch($wkday) {
        case 'Monday': $numDaysToMon = 0; break;
        case 'Tuesday': $numDaysToMon = 1; break;
        case 'Wednesday': $numDaysToMon = 2; break;
        case 'Thursday': $numDaysToMon = 3; break;
        case 'Friday': $numDaysToMon = 4; break;
        case 'Saturday': $numDaysToMon = 5; break;
        case 'Sunday': $numDaysToMon = 6; break;   
    }

    // Timestamp of the monday for that week
    $monday = mktime('0','0','0', $month, $day-$numDaysToMon, $year);

    $seconds_in_a_day = 86400;

    // Get date for 7 days from Monday (inclusive)
    for($i=0; $i<7; $i++)
    {
        $dates[$i] = date('Y-m-d',$monday+($seconds_in_a_day*$i));
    }

    return $dates;
}

Output from week_from_monday('07-10-2008') gives:

Array
(
    [0] => 2008-10-06
    [1] => 2008-10-07
    [2] => 2008-10-08
    [3] => 2008-10-09
    [4] => 2008-10-10
    [5] => 2008-10-11
    [6] => 2008-10-12
)
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