Question

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 1

PHP

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

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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 )