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(PHP 4 >= 4.0.1, PHP 5, PHP 7, PHP 8)
array_diff — Computes the difference of arrays
array_diff(array $array, array ...$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.
array
The array to compare from
arrays
Arrays to compare against
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.
| Version | Description |
|---|---|
| 8.0.0 | This function can now be called with only one parameter. Formerly, at least two parameters have been required. |
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);
// $result now contains one instance of S('a');
?>
To use an alternate comparison function, see array_udiff() .
Note :
This function only checks one dimension of a n-dimensional array. Of course you can check deeper dimensions by using
array_diff($array1[0], $array2[0]);.
(PHP 4 >= 4.3.0, PHP 5, PHP 7, PHP 8)
array_diff_assoc — Computes the difference of arrays with additional index check
array_diff_assoc(array $array, array ...$arrays): array
Compares
array
against
arrays
and returns the difference. Unlike
array_diff()
the array keys are also used in the comparison.
array
The array to compare from
arrays
Arrays to compare against
Returns an
array
containing all the values from
array
that are not present in any of the other arrays.
| Version | Description |
|---|---|
| 8.0.0 | This function can now be called with only one parameter. Formerly, at least two parameters have been required. |
Example #1 array_diff_assoc() example
In this example you see the
"a" => "green"
pair is present in both arrays and thus it is not in the output from the function. Unlike this, the pair
0 => "red"
is in the output because in the second argument
"red"
has key which is
1
.
<?php
$array1 = array("a" => "green", "b" => "brown", "c" => "blue", "red");
$array2 = array("a" => "green", "yellow", "red");
$result = array_diff_assoc($array1, $array2);
print_r($result);
?>
The above example will output:
Array
(
[b] => brown
[c] => blue
[0] => red
)
Example #2 array_diff_assoc() example
Two values from
key => value
pairs are considered equal only if
(string) $elem1 === (string)
$elem2
. In other words a strict check takes place so the string representations must be the same.
<?php
$array1 = array(0, 1, 2);
$array2 = array("00", "01", "2");
$result = array_diff_assoc($array1, $array2);
print_r($result);
?>
The above example will output:
Array
(
[0] => 0
[1] => 1
)
Note : This function only checks one dimension of a n-dimensional array. Of course you can check deeper dimensions by using, for example,
array_diff_assoc($array1[0], $array2[0]);.
Note : Ensure you pass arguments in the correct order when comparing similar arrays with more keys. The new array should be the first in the list.
(PHP 5 >= 5.1.0, PHP 7, PHP 8)
array_diff_key — Computes the difference of arrays using keys for comparison
array_diff_key(array $array, array ...$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.
array
The array to compare from
arrays
Arrays to compare against
Returns an
array
containing all the entries from
array
whose keys are absent from all of the other arrays.
| Version | Description |
|---|---|
| 8.0.0 | This function can now be called with only one parameter. Formerly, at least two parameters have been required. |
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]);.
(PHP 5, PHP 7, PHP 8)
array_diff_uassoc — Computes the difference of arrays with additional index check which is performed by a user supplied callback function
array_diff_uassoc(array $array, array ...$arrays, callable $key_compare_func): array
Compares
array
against
arrays
and returns the difference. Unlike
array_diff()
the array keys are used in the comparison.
Unlike array_diff_assoc() a user supplied callback function is used for the indices comparison, not internal function.
array
The array to compare from
arrays
Arrays to compare against
key_compare_func
The comparison 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.
callback(mixed $a, mixed $b): int
Returns an
array
containing all the entries from
array
that are not present in any of the other arrays.
Example #1 array_diff_uassoc() example
The
"a" => "green"
pair is present in both arrays and thus it is not in the output from the function. Unlike this, the pair
0 => "red"
is in the output because in the second argument
"red"
has key which is
1
.
<?php
function key_compare_func($a, $b)
{
if ($a === $b) {
return 0;
}
return ($a > $b)? 1:-1;
}
$array1 = array("a" => "green", "b" => "brown", "c" => "blue", "red");
$array2 = array("a" => "green", "yellow", "red");
$result = array_diff_uassoc($array1, $array2, "key_compare_func");
print_r($result);
?>
The above example will output:
Array
(
[b] => brown
[c] => blue
[0] => red
)
The equality of 2 indices is checked by the user supplied callback function.
Note :
This function only checks one dimension of a n-dimensional array. Of course you can check deeper dimensions by using, for example,
array_diff_uassoc($array1[0], $array2[0], "key_compare_func");.
(PHP 5 >= 5.1.0, PHP 7, PHP 8)
array_diff_ukey — Computes the difference of arrays using a callback function on the keys for comparison
array_diff_ukey(array $array, array ...$arrays, callable $key_compare_func): 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.
Unlike array_diff_key() a user supplied callback function is used for the indices comparison, not internal function.
array
The array to compare from
arrays
Arrays to compare against
key_compare_func
The comparison 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.
callback(mixed $a, mixed $b): int
Returns an
array
containing all the entries from
array
that are not present in any of the other arrays.
Example #1 array_diff_ukey() example
<?php
function key_compare_func($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, $array2, 'key_compare_func'));
?>
The above example will output:
array(2) {
["red"]=>
int(2)
["purple"]=>
int(4)
}
Note :
This function only checks one dimension of a n-dimensional array. Of course you can check deeper dimensions by using
array_diff_ukey($array1[0], $array2[0], 'callback_func');.
(PHP 4 >= 4.2.0, PHP 5, PHP 7, PHP 8)
array_fill — Fill an array with values
array_fill(int $start_index, int $count, mixed $value): array
Fills an array with
count
entries of the value of the
value
parameter, keys starting at the
start_index
parameter.
start_index
The first index of the returned array.
If
start_index
is negative, the first index of the returned array will be
start_index
and the following indices will start from zero prior to PHP 8.0.0; as of PHP 8.0.0, negative keys are incremented normally (see example).
count
Number of elements to insert. Must be greater than or equal to zero, and less than or equal to
2147483647
.
value
Value to use for filling
Returns the filled array
Throws a
ValueError
if
count
is out of range.
| Version | Description |
|---|---|
| 8.0.0 |
array_fill()
now throws a
ValueError
if
count
is out of range; previously
E_WARNING
was raised, and the function returned
false
.
|
Example #1 array_fill() example
<?php
$a = array_fill(5, 6, 'banana');
print_r($a);
?>
The above example will output:
Array
(
[5] => banana
[6] => banana
[7] => banana
[8] => banana
[9] => banana
[10] => banana
)
Example #2 array_fill() example with a negative start index
<?php
$a = array_fill(-2, 4, 'pear');
print_r($a);
?>
Output of the above example in PHP 7:
Array
(
[-2] => pear
[0] => pear
[1] => pear
[2] => pear
)
Output of the above example in PHP 8:
Array
(
[-2] => pear
[-1] => pear
[0] => pear
[1] => pear
)
Note that index
-1
is not present prior to PHP 8.0.0.
See also the Arrays section of manual for a detailed explanation of negative keys.