# array_diff_ukey

(PHP 5 >= 5.1.0)

array_diff_ukey — Computes the difference of arrays using a callback function on the keys for comparison

### Description

array array_diff_ukey ( array `$array1` , array `$array2` [, array `$ ...` ], callback `$key_compare_func` )

Compares the keys from `array1` against the keys from `array2` and returns the difference. This function is like array_diff() except the comparison is done on the keys instead of the values.

Unlike array_diff_key() an user supplied callback function is used for the indices comparision, not internal function.

### Parameters

`array1`

  The array to compare from

`array2`

  An array to compare against

`...`

  More arrays to compare against

`key_compare_func`

  callback function to use. The callback function must return an integer less than, equal to, or greater than zero if the first argument is considered to be respectively less than, equal to, or greater than the second.

### Return Values

Returns an array containing all the entries from `array1` that are not present in any of the other arrays.

### Examples

Example#1 array_diff_ukey() example

`<?php
function key_compare_func($key1, $key2)
{
if ($key1 == $key2)
return 0;
else if ($key1 > $key2)
return 1;
else
return -1;
}
$array1 = array('blue' => 1, 'red' => 2, 'green' => 3, 'purple' => 4);
$array2 = array('green' => 5, 'blue' => 6, 'yellow' => 7, 'cyan' => 8);
var_dump(array_diff_ukey($array1, $array2, 'key_compare_func'));
?>`

The above example will output:

    array(2) {
      ["red"]=>
      int(2)
      ["purple"]=>
      int(4)
    }

### Notes

> Note: This function only checks one dimension of a n-dimensional array. Of course you can check deeper dimensions by using array_diff_ukey($array1[0], $array2[0], 'callback_func');.

### See Also

- array_diff()
- array_udiff()
- array_diff_assoc()
- array_diff_uassoc()
- array_udiff_assoc()
- array_udiff_uassoc()
- array_diff_key()
- array_intersect()
- array_intersect_assoc()
- array_intersect_uassoc()
- array_intersect_key()
- array_intersect_ukey()