array_diff_key
(PHP 5 >= 5.1.0, PHP 7, PHP 8)
array_diff_key — Computes the difference of arrays using keys for comparison
Description
$array, array ...$arrays): array
Compares the keys from array against the keys
from arrays and returns the difference.
This function is like array_diff() except the
comparison is done on the keys instead of the values.
Parameters
-
array -
The array to compare from
-
arrays -
Arrays to compare against
Return Values
Returns an array containing all the entries from
array whose keys are absent from all of the
other arrays.
Changelog
| Version | Description |
|---|---|
| 8.0.0 | This function can now be called with only one parameter. Formerly, at least two parameters have been required. |
Examples
Example #1 array_diff_key() example
The two keys from the key => value pairs are
considered equal only if
(string) $key1 === (string) $key2 . In other words
a strict type check is executed so the string representation must be
the same.
<?php
$array1 = array('blue' => 1, 'red' => 2, 'green' => 3, 'purple' => 4);
$array2 = array('green' => 5, 'yellow' => 7, 'cyan' => 8);
var_dump(array_diff_key($array1, $array2));
?>
The above example will output:
array(3) {
["blue"]=>
int(1)
["red"]=>
int(2)
["purple"]=>
int(4)
}
<?php
$array1 = array('blue' => 1, 'red' => 2, 'green' => 3, 'purple' => 4);
$array2 = array('green' => 5, 'yellow' => 7, 'cyan' => 8);
$array3 = array('blue' => 6, 'yellow' => 7, 'mauve' => 8);
var_dump(array_diff_key($array1, $array2, $array3));
?>
The above example will output:
array(2) {
["red"]=>
int(2)
["purple"]=>
int(4)
}
Notes
Note:
This function only checks one dimension of a n-dimensional array. Of course you can check deeper dimensions by using
array_diff_key($array1[0], $array2[0]);.
See Also
- array_diff() - Computes the difference of arrays
- array_udiff() - Computes the difference of arrays by using a callback function for data comparison
- array_diff_assoc() - Computes the difference of arrays with additional index check
- array_diff_uassoc() - Computes the difference of arrays with additional index check which is performed by a user supplied callback function
- array_udiff_assoc() - Computes the difference of arrays with additional index check, compares data by a callback function
- array_udiff_uassoc() - Computes the difference of arrays with additional index check, compares data and indexes by a callback function
- array_diff_ukey() - Computes the difference of arrays using a callback function on the keys for comparison
- array_intersect() - Computes the intersection of arrays
- array_intersect_assoc() - Computes the intersection of arrays with additional index check
- array_intersect_uassoc() - Computes the intersection of arrays with additional index check, compares indexes by a callback function
- array_intersect_key() - Computes the intersection of arrays using keys for comparison
- array_intersect_ukey() - Computes the intersection of arrays using a callback function on the keys for comparison
