#18532 [Com]: date('W'...) returns wrong weeknumbers

ID: 18532 Comment by: tmus@get2net.dk Reported By: tmus@get2net.dk Status: Closed Bug Type: Date/time related Operating System: Linux / Windows XP PHP Version: 4.2.1 Assigned To: georg New Comment: I was just wondering why the fix does not seem to be in the 4.2.3 release - am I incorrect or what? I have not installed it yet (prod system) but the source code for the 'W' function does not appear to have changed?!? Previous Comments: ------------------------------------------------------------------------ [2002-07-26 12:51:44] georg@php.net This bug has been fixed in CVS. You can grab a snapshot of the CVS version at http://snaps.php.net/. In case this was a documentation problem, the fix will show up soon at http://www.php.net/manual/. In case this was a PHP.net website problem, the change will show up on the PHP.net site and on the mirror sites. Thank you for the report, and for helping us make PHP better. ------------------------------------------------------------------------ [2002-07-26 04:06:15] georg@php.net Yes, you're right. Looks like the code is a little bit buggy. I'll fix that. ------------------------------------------------------------------------ [2002-07-25 11:45:49] pguillot@paanjaru.com %W returns some 0th week of the year : $deb = mktime( 0, 0, 0, 1, 1, '2002'); print 'Week test for day '. $deb ."\n"; print 'for day '. strftime( '%d-%m-%Y', $deb) ."\n"; print 'strftime %Y-%W gives '; print strftime( '%Y-%W', $deb ) . "\n"; When run, it gives Week test for day 1009839600 (01-01-2002) strftime %Y-%W gives 2002-00 So, this will lead to a lot of problems when using week computations ... you can use function D2YWeeknum( $date ) { // // pg 20020719 pguillot@paanjaru.com // for intentis.net // Inspired Algorithm used:From Klaus Tondering's Calendar document (The Authority/Guru) // http://www.tondering.dk/claus/calendar.html // // It's not yet possible in the port to select the week start. $supplemental = ""; $this_date = getdate( $date ); $year = $this_date['year']; $month = $this_date['mon']; $day = $this_date['mday']; $a = floor( ( 14 - $month ) / 12 ); $y = $year + 4800 - $a; $m = $month + 12 * $a - 3; $J = $day + floor( ( 153 * $m + 2 ) / 5 ) + 365 * $y + floor( $y / 4) - floor( $y / 100 ) + floor( $y / 400 ) - 32045; $d4 = ( ( ( $J + 31741 - ( $J % 7 ) ) % 146097) % 36524) % 1461; $L = floor( $d4 / 1460); $d1 = ( ( $d4 - $L ) % 365 ) + $L; $week = floor( $d1 / 7 ) + 1; if ( $week < 10 ) { $supplemental = '0'; } return( $year .'-'. $supplemental . $week ); } wich will gives you a correct number ... ------------------------------------------------------------------------ [2002-07-25 09:19:41] tmus@get2net.dk I made a small C function that's supposed to carry out the calculation(based on the W handling code of the php datetime.c file) Please notice that I am in no way a math wiz and that this routine is likely optimizable and maybe even buggy. However, to the depth of my tests, it seems to do the trick... I provide it here as a "it-could-be-done-something-like-this" kinda thing... I'm sorry I'm unable to write a proper patch for you to test, but I have no working compiler at the moment. Please take it for a spin if you like or use it for inspiration. Also check out the link mentioned elsewhere in the report. He has a lot of sample script etc. that may provide you with useful information... Here goes the code ----------------------------------- /********************************************************* * * tm_wday: day of week(0=sun - 6=sat) * tm_yday: day of year(0=jan 1. - 364 or 365(leap years) * tm_leap: current year leap flag(0 if not leap - 1 if leap) * ly_leap: last years leap flag(0 if not leap - 1 if leap) * *********************************************************/ int week(int tm_wday, int tm_yday, int tm_leap, int ly_leap){ int yd, fd, ld, wk, wd; wd = ( tm_wday == 0 ) ? 7 : tm_wday; yd = tm_yday + 1; fd = ( 7 + ( wd - yd ) % 7 ) % 7; ld = ( fd + ( 364 + tm_leap ) %7 ) %7; wk = ( ( yd + fd - 1 ) / 7 ) + 1; if ( fd > 3 ) wk--; if ( ld < 3 && yd > ( ( 364 + tm_leap ) - ld ) ) wk = 1; if( wk == 0 ) wk = week( tm_wday, 364+ly_leap, ly_leap, 0 ); return( wk ); } --------------------------------------------- ------------------------------------------------------------------------ [2002-07-24 14:57:12] tmus@get2net.dk I'm sorry, but did you read my bug report before closing it as bogus..? it returns Week 53 for TUESDAY 31 Dec. and Week 1 for the day AFTER that - This is incorrect!!! The way I read the ISO date specification, it is NOT possible for the same week MON-SUN to have two different week numbers!!! And the ISO specifies that a WEEK is STARTING on monday and ENDING on sunday, so howcome the weeknumber changes between Tuesday and Wednesday... Please just try the code i sent you guys! ------------------------------------------------------------------------ The remainder of the comments for this report are too long. To view the rest of the comments, please view the bug report online at http://bugs.php.net/18532 -- Edit this bug report at http://bugs.php.net/?id=18532&edit=1