获取所有阵列中显示的所有密钥

Question

I have some arrays, for example

$arr[0]=array(k1=>1,k2=>1,k3=>1);
$arr[1]=array(k2=>1,k3=>1,k4=>1);
$arr[2]=array(k3=>1,k4=>1,k5=>1);

So, I need to get all the keys (dynamically, the number of arrays can differ), presented in all arrays. In this case it is k3 key. So the result should be array('k3'=>1)

I suggest it could be achieved by multiple loops, but probably there's some easier way.

Answer 1

You need the function array_intersect_key():

<?php

$arr1 = array('k1' => 1, 'k2' => 1, 'k3' => 1);
$arr2 = array('k2' => 1, 'k3' => 1, 'k4' => 1);
$arr3 = array('k3' => 1, 'k4' => 1, 'k5' => 1);

print_r(
    array_intersect_key($arr1, $arr2, $arr3)
);

Output:

Array
(
    [k3] => 1
)