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<?php $datetime = new \DateTime('2016-10-01'); while ($datetime->format('m') === '10') { $datetime->add(new \DateInterval('P1D')); var_dump($datetime->format('l')); }
Output for 5.6.0 - 5.6.40, 7.0.0 - 7.0.33, 7.1.0 - 7.1.33, 7.2.0 - 7.2.33, 7.3.0 - 7.3.33, 7.4.0 - 7.4.33, 8.0.0 - 8.0.30, 8.1.0 - 8.1.28, 8.2.0 - 8.2.19, 8.3.0 - 8.3.7
string(6) "Sunday" string(6) "Monday" string(7) "Tuesday" string(9) "Wednesday" string(8) "Thursday" string(6) "Friday" string(8) "Saturday" string(6) "Sunday" string(6) "Monday" string(7) "Tuesday" string(9) "Wednesday" string(8) "Thursday" string(6) "Friday" string(8) "Saturday" string(6) "Sunday" string(6) "Monday" string(7) "Tuesday" string(9) "Wednesday" string(8) "Thursday" string(6) "Friday" string(8) "Saturday" string(6) "Sunday" string(6) "Monday" string(7) "Tuesday" string(9) "Wednesday" string(8) "Thursday" string(6) "Friday" string(8) "Saturday" string(6) "Sunday" string(6) "Monday" string(7) "Tuesday"

preferences:
223.73 ms | 405 KiB | 293 Q