array_diff
(PHP 4 >= 4.0.1, PHP 5, PHP 7, PHP 8)
array_diff — Computes the difference of arrays
Description
$array
, array ...$arrays
): array
Compares array
against one or more other arrays and
returns the values in array
that are not present in
any of the other arrays.
Parameters
-
array
-
The array to compare from
-
arrays
-
Arrays to compare against
Return Values
Returns an array containing all the entries from
array
that are not present in any of the other arrays.
Keys in the array
array are preserved.
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() example
<?php
$array1 = array("a" => "green", "red", "blue", "red");
$array2 = array("b" => "green", "yellow", "red");
$result = array_diff($array1, $array2);
print_r($result);
?>
Multiple occurrences in $array1 are all treated the same way. This will output :
Array ( [1] => blue )
Example #2 array_diff() example with non-matching types
Two elements are considered equal if and only if
(string) $elem1 === (string) $elem2
. That is,
when the string representation is the same.
<?php
// This will generate a Notice that an array cannot be cast to a string.
$source = [1, 2, 3, 4];
$filter = [3, 4, [5], 6];
$result = array_diff($source, $filter);
// Whereas this is fine, since the objects can cast to a string.
class S {
private $v;
public function __construct(string $v) {
$this->v = $v;
}
public function __toString() {
return $this->v;
}
}
$source = [new S('a'), new S('b'), new S('c')];
$filter = [new S('b'), new S('c'), new S('d')];
$result = array_diff($source, $filter);
// $result now contains one instance of S('a');
?>
To use an alternate comparison function, see array_udiff().
Notes
Note:
This function only checks one dimension of a n-dimensional array. Of course you can check deeper dimensions by using
array_diff($array1[0], $array2[0]);
.
See Also
- array_diff_assoc() - Computes the difference of arrays with additional index check
- array_udiff() - Computes the difference of arrays by using a callback function for data comparison
- array_intersect() - Computes the intersection of arrays
- array_intersect_assoc() - Computes the intersection of arrays with additional index check