Bug #77941 [Com]: strtotime "next <weekday>" are off by one for dates parsed from calendar week

Edit report at https://bugs.php.net/bug.php?id=77941&edit=1 ID: 77941 Comment by: a at b dot c dot de Reported by: mail at cebe dot cc Summary: strtotime "next <weekday>" are off by one for dates parsed from calendar week Status: Not a bug Type: Bug Package: Date/time related Operating System: Linux PHP Version: 7.3.4 Assigned To: cmb Block user comment: N Private report: N New Comment: How would using the ISO year make a difference in the middle of April? And why would it cause a shift of one day? Consider echo date("o-W-N", strtotime("2019W16 next tuesday")); Between 5.1.6 and 5.2.0 the output changes from Tuesday of Week 16 (2019-16-2) to Monday of Week 17 (2019-17-1). Tuesday isn't Monday even in the ISO calendar. Previous Comments: ------------------------------------------------------------------------ [2019-04-25 13:21:34] cmb@php.net Thank you for taking the time to write to us, but this is not a bug. Please double-check the documentation available at http://www.php.net/manual/ and the instructions on how to report a bug at http://bugs.php.net/how-to-report.php You have to use 'o' in combination with 'W'. ------------------------------------------------------------------------ [2019-04-25 09:25:25] mail at cebe dot cc Description: ------------ when working on a date parsed from calendar week from the pattern {YYYY}W{WW}, e.g. "2019W16" strtotime returns the date of Monday in the calendar week 16 in the year 2019, which is 2019-04-15. When this is combinated with a "next <weekday>" e.g. "2019W16 next friday", the result is one off, in this case 2019-04-18, which is Thursday of that week, not Friday. Giving "2019-04-15 next friday" gives the correct date: 2019-04-19. According to my test script, this is broken since PHP 5.2, while working fine in 5.1: https://3v4l.org/0s4Ns Test script: --------------- <?php // see also https://3v4l.org/0s4Ns if (function_exists('date_default_timezone_set')) date_default_timezone_set("UTC"); echo "works as expected:\n"; echo date("Y-m-d H:i:s", strtotime("2019W14")) . " should be 2019-04-01\n"; echo date("Y-m-d H:i:s", strtotime("2019W15")) . " should be 2019-04-08\n"; echo date("Y-m-d H:i:s", strtotime("2019W16")) . " should be 2019-04-15\n\n"; echo "off by one:\n"; echo date("Y-m-d H:i:s", strtotime("2019W16 next tuesday")) . " should be 2019-04-16\n"; echo date("Y-m-d H:i:s", strtotime("2019W16 next wednesday")) . " should be 2019-04-17\n"; echo date("Y-m-d H:i:s", strtotime("2019W16 next thursday")) . " should be 2019-04-18\n"; echo date("Y-m-d H:i:s", strtotime("2019W16 next friday")) . " should be 2019-04-19\n"; echo date("Y-m-d H:i:s", strtotime("2019W16 next saturday")) . " should be 2019-04-20\n"; echo date("Y-m-d H:i:s", strtotime("2019W16 next sunday")) . " should be 2019-04-21\n"; echo date("Y-m-d H:i:s", strtotime("2019W16 next monday")) . " should be 2019-04-22\n\n"; echo "works as expected:\n"; echo date("Y-m-d H:i:s", strtotime("2019-04-15 next monday")) . " should be 2019-04-22\n"; echo date("Y-m-d H:i:s", strtotime("2019-04-15 next friday")) . " should be 2019-04-19\n"; echo date("Y-m-d H:i:s", strtotime("2019-04-15 next thursday")) . " should be 2019-04-18\n"; Expected result: ---------------- see above. Actual result: -------------- see above. ------------------------------------------------------------------------ -- Edit this bug report at https://bugs.php.net/bug.php?id=77941&edit=1