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<?php $a = ['a'=>1,'b'=>2,'c'=>3]; $b = ['a'=>'aa','b'=>'bb']; var_dump(array_combine( array_map( function($key) use ($b) { return isset($b[$key]) ? $b[$key] : $key; }, array_keys($a) ), array_values($a) ));

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40.24 ms | 402 KiB | 5 Q