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run code in 300+ PHP versions simultaneously
<?php foreach (range(0,8) as $days) { $a1 = new DateTime('2016-03-07 18:02:40'); $a1->modify("+$days days"); $a1->modify('next week'); echo $days . PHP_EOL; var_dump($a1->format('d/m/Y')); }
Output for 5.6.23 - 5.6.40, 7.0.8 - 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 - 8.1.27, 8.2.0 - 8.2.17, 8.3.0 - 8.3.4
0 string(10) "14/03/2016" 1 string(10) "14/03/2016" 2 string(10) "14/03/2016" 3 string(10) "14/03/2016" 4 string(10) "14/03/2016" 5 string(10) "14/03/2016" 6 string(10) "14/03/2016" 7 string(10) "21/03/2016" 8 string(10) "21/03/2016"
Output for 5.5.0 - 5.5.38, 5.6.0 - 5.6.22, 7.0.0 - 7.0.7
0 string(10) "14/03/2016" 1 string(10) "14/03/2016" 2 string(10) "14/03/2016" 3 string(10) "14/03/2016" 4 string(10) "14/03/2016" 5 string(10) "14/03/2016" 6 string(10) "21/03/2016" 7 string(10) "21/03/2016" 8 string(10) "21/03/2016"

preferences:
232.56 ms | 402 KiB | 325 Q