[matt.simpson]

Hello,
Subject pretty much says it.

I haven't a clue of how to go about doing this accuratly.

Basically, I have an ISO-8601 week number, ie: 47 and the year, ie: 2004

I need to know any of the 7 days of year, ie: 124 (preferrably the first day) of that week...

If anyone has a light to shed, please post.

Thanks,
Matt Simpson

[YourPHPPro]

Would this help ?

Code:

matt at crx4u dot com
30-Oct-2002 06:53

Here's a pair of functions to convert a date to an ISO 8601 year/week and vice versa.

function yearweek($date="") {
   if (!$date) $date = mktime();
   $yearweek =  strftime("%G%V", $date);
   return $yearweek;
}

function dateEndYearweek($yearweek) {
   $weekEndDay = 0;  // 0 = Sunday.
   $year = (int) substr($yearweek, 0, 4);
   $week = (int) substr($yearweek, -2, 2);
   // We know that the 4th Jan is always in week 01, 11th Jan in week 02, ...
   // so day (4 + (w-1)*7) is in week w.
   $dayOfYear = 4 + (($week - 1) * 7);
   $date = mktime(0, 0, 0, 1, $dayOfYear, $year);
   // Find the last day of this week.
   $dayOfWeek = date("w", $date);
   $daysToAdd = ($weekEndDay - $dayOfWeek + 7) % 7;
   $date += $daysToAdd * 24*60*60;
   return $date;
}

http://www.php.net/strftime