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<?php function datediffInWeeks($date1, $date2) { if($date1 > $date2) return datediffInWeeks($date2, $date1); $first = DateTime::createFromFormat('m/d/Y', $date1); $second = DateTime::createFromFormat('m/d/Y', $date2); return floor($first->diff($second)->days/7); } $q = new DateTime('First day of 2015'); var_dump($q);// 21
based on 0ZsAG
Output for 5.4.30 - 5.4.45, 5.6.28, 7.0.20 - 7.2.0
object(DateTime)#1 (3) { ["date"]=> string(26) "2015-11-01 20:15:00.000000" ["timezone_type"]=> int(3) ["timezone"]=> string(16) "Europe/Amsterdam" }
Output for 5.5.24, 5.5.35, 5.6.21, 7.0.6
object(DateTime)#1 (3) { ["date"]=> string(26) "2016-05-01 20:15:00.000000" ["timezone_type"]=> int(3) ["timezone"]=> string(16) "Europe/Amsterdam" }
Output for 5.5.25 - 5.5.30, 5.5.34, 5.6.8 - 5.6.14, 5.6.20, 7.0.5
object(DateTime)#1 (3) { ["date"]=> string(26) "2016-04-01 20:15:00.000000" ["timezone_type"]=> int(3) ["timezone"]=> string(16) "Europe/Amsterdam" }
Output for 5.5.31 - 5.5.33, 5.6.15 - 5.6.19, 7.0.0 - 7.0.4
object(DateTime)#1 (3) { ["date"]=> string(26) "2016-03-01 20:15:00.000000" ["timezone_type"]=> int(3) ["timezone"]=> string(16) "Europe/Amsterdam" }
Output for 5.3.19 - 5.4.29
object(DateTime)#1 (3) { ["date"]=> string(19) "2015-11-01 20:15:00" ["timezone_type"]=> int(3) ["timezone"]=> string(16) "Europe/Amsterdam" }