Question

$array1 = ['key1'=>'val1', 'key2'=>'val2', 'key3'=>'val3']
$array2 = ['key1','key3']

I want to get all elements from array1 that has keys in array2.
So the result should be:

$result = ['key1'=>'val1', 'key3'=>'val3']

I tried array_intersect_key($array1, $array2) but that doesn’t work. What is the fastest way to get the above result?

Edit: Forgot to mention that array2 maybe a associative array or single dimension.

Answer 1

You need to make key1 and key2 the keys in the second array before you can use array_intersect_key(): use array_flip() to do that

$result = array_intersect_key($array1,array_flip($array2));

EDIT

It doesn’t matter if $array2 is associative or not:

$array1 = array('key1'=>'val1', 'key2'=>'val2', 'key3'=>'val3');
$array2 = array('first'=>'key1','second'=>'key3');

$filteredData = array_intersect_key($array1,array_flip($array2));
var_dump($filteredData);

still gives

array
  'key1' => string 'val1' (length=4)
  'key3' => string 'val3' (length=4)