3v4l.org

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<?php $input = [1=>[1=>2,2=>"somet&hing"],2=>[1,2],3=>"hel&lo"]; array_walk_recursive($input, function (&$value) { $value = htmlentities($value); }); print_r($input);
Output for 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 - 8.1.33, 8.2.0 - 8.2.29, 8.3.0 - 8.3.26, 8.4.1 - 8.4.14
Array ( [1] => Array ( [1] => 2 [2] => somet&amp;hing ) [2] => Array ( [0] => 1 [1] => 2 ) [3] => hel&amp;lo )

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178.9 ms | 408 KiB | 5 Q