The array_diff_key() function compares array keys, and returns the differences. It returns an array containing the entries from the first array that are not present in any of the other arrays.
Syntax
array_diff_key(arr1, arr2, arr3, arr4, ...)
Parameters
arr1 − Array to compare from. Required.
arr2 − Array to compare against. Required.
arr3 − You can add more arrays to compare. Optional.
arr4 − You can add more arrays to compare. Optional.
Return
The array_diff_key() function returns an array containing the entries from the first array that are not present in any of the other arrays.
Example
<?php
$arr1 = array('car' => 10, 'bus' => 15, 'truck' => 22);
$arr2 = array('motorbike' => 35, 'bus' => 42);
$res = array_diff_key($arr1,$arr2);
print_r($res);
?>
Output
Array ( [car] => 10 [truck] => 22 )