3v4l.org

run code in 300+ PHP versions simultaneously
<?php // Everything you enter here will be executed by our servers. Try it! $wineBuys = array ( '2013-09-12' => 20, '2013-09-13' => 10, '2013-09-14' => 49 ); $hamBuys = array ( '2013-09-12' => 1, '2013-09-13' => 16, '2013-09-14' => 2 ); $cheeseBuys = array ( '2013-09-12' => 5, '2013-09-13' => 6, '2013-09-14' => 12 ); $calcByDate = array(); foreach ($wineBuys as $key => $value) { if (! array_key_exists($key, $calcByDate)) { $calcByDate[$key] = array($wineBuys[$key]); } else { $calcByDate[$key][] = $wineBuys[$key]; } } print_r($calcByDate);
Output for 4.3.0 - 4.3.11, 4.4.0 - 4.4.9, 5.0.0 - 5.0.5, 5.1.0 - 5.1.6, 5.2.0 - 5.2.17, 5.3.0 - 5.3.29, 5.4.0 - 5.4.45, 5.5.24 - 5.5.35, 5.6.8 - 5.6.28, 7.0.0 - 7.0.20, 7.1.0 - 7.1.25, 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 - 8.2.18, 8.3.0 - 8.3.6
Array ( [2013-09-12] => Array ( [0] => 20 ) [2013-09-13] => Array ( [0] => 10 ) [2013-09-14] => Array ( [0] => 49 ) )

preferences:
229.97 ms | 406 KiB | 329 Q