3v4l.org

run code in 300+ PHP versions simultaneously
<?php $arrayFirst = [ "index" => [ 'a' => '1', ], [ 'a' => '2', ] ]; $arraySecond = [ "index" => [ 'b' => '1', ], [ 'b' => '2', ] ]; foreach ($arrayFirst as $k => &$row) { $row = array_merge($row, $arraySecond[$k]); } var_export($arrayFirst);
Output for 7.4.0 - 7.4.33, 8.0.1 - 8.0.30, 8.1.0 - 8.1.28, 8.2.0 - 8.2.18, 8.3.0 - 8.3.7
array ( 'index' => array ( 'a' => '1', 'b' => '1', ), 0 => array ( 'a' => '2', 'b' => '2', ), )
preferences:
124.34 ms | 402 KiB | 122 Q