How to filter an associative arrays using array of keys in PHP?
array_intersect_key($A,array_combine($B,$B))
or better: array_intersect_key($my_array, array_flip($allowed))
from the question: PHP: How to use array_filter() to filter array keys?
Here's a simple solution which checks that the key exists in $A before appending it to $C
$A = array('a'=>'book', 'b'=>'pencil', 'c'=>'pen');$B = array('a', 'b');$C = array();foreach ($B as $bval) { // If the $B key exists in $A, add it to $C if (isset($A[$bval])) $C[$bval] = $A[$bval];}var_dump($C);// Prints:array(2) { ["a"]=> string(4) "book" ["b"]=> string(6) "pencil"}