(PHP 5 >= 5.1.0, PHP 7)
array_diff_key — Computes the difference of arrays using keys for comparison
$array1
, array $array2
[, array $...
] ) : array
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.
array1The array to compare from
array2An array to compare against
...More arrays to compare against
Returns an array containing all the entries from
array1 whose keys are absent from all of the
other arrays.
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, $array3));
?>
The above example will output:
array(2) {
["red"]=>
int(2)
["purple"]=>
int(4)
}
Note:
This function only checks one dimension of a n-dimensional array. Of course you can check deeper dimensions by using
array_diff_key($array1[0], $array2[0]);.