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<?php $a = array('a' => 1, 'b' => array('c' => 3, 'd' => 4)); $b = array('a' => 3, 'b' => array('d' => 5, 'e' => 6)); print_r(array_merge_recursive($a, $b));
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 ( [a] => Array ( [0] => 1 [1] => 3 ) [b] => Array ( [c] => 3 [d] => Array ( [0] => 4 [1] => 5 ) [e] => 6 ) )

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