note 100385 added to function.strftime

%V may fail with some systems (Windows XP, at least). Here is a function that should work to get the week number of a day (timestamped), according to ISO 8601. "should work" as in "it is working with my understanding of this norm", where 1st of january can be week 52, 53 or 01. Hopefully. testing (php_uname("s") == "Windows NT") or equivalent can be an option (when switching between Wampserver and a GNU server, for instance). Please, erase and correct my message if there is any error. <?php function week_isonumber ($time) { // When strftime("%V") fails, some unoptimized workaround // // http://en.wikipedia.org/wiki/ISO_8601 : week 1 is "the week with the year's first Thursday in it (the formal ISO definition)" $year = strftime("%Y", $time); $first_day = strftime("%w", mktime(0, 0, 0, 1, 1, $year)); $last_day = strftime("%w", mktime(0, 0, 0, 12, 31, $year)); $number = $isonumber = strftime("%W", $time); // According to strftime("%W"), 1st of january is in week 1 if and only if it is a monday if ($first_day == 1) $isonumber--; // 1st of january is between monday and thursday; starting (now) at 0 when it should be 1 if ($first_day >= 1 && $first_day <= 4) $isonumber++; else if ($number == 0) $isonumber = week_isonumber(mktime(0, 0, 0, 12, 31, $year - 1)); if ($isonumber == 53 && ($last_day == 1 || $last_day == 2 || $last_day == 3)) $isonumber = 1; return sprintf("%02d", $isonumber); } ?> ---- Server IP: 69.147.83.197 Probable Submitter: 78.241.128.114 ---- Manual Page -- http://www.php.net/manual/en/function.strftime.php Edit -- https://master.php.net/note/edit/100385 Del: integrated -- https://master.php.net/note/delete/100385/integrated Del: useless -- https://master.php.net/note/delete/100385/useless Del: bad code -- https://master.php.net/note/delete/100385/bad+code Del: spam -- https://master.php.net/note/delete/100385/spam Del: non-english -- https://master.php.net/note/delete/100385/non-english Del: in docs -- https://master.php.net/note/delete/100385/in+docs Del: other reasons-- https://master.php.net/note/delete/100385 Reject -- https://master.php.net/note/reject/100385 Search -- https://master.php.net/manage/user-notes.php