array_filter

Description
Syntax
Examples
Links

Description

The array_filter of Array for PHP filters elements of an array using a callback function.

Syntax

array_filter(
    array $array,
    ?callable $callback = null,
    int $mode = 0
): array

Parameters

array

The array to iterate over.

callback

The callback function to use.

If no callback is supplied, all empty entries of array will be removed.

mode

Flag determining what arguments are sent to callback:

Value	Constant	Description
0		pass value as the only argument to callback
1	ARRAY_FILTER_USE_BOTH	pass both value and key as arguments to callback
2	ARRAY_FILTER_USE_KEY	pass key as the only argument to callback

Return

Returns the filtered array.

Examples

1 · array

<?

$array =
[
    0 => null,
    1 => false,
    2 => 0,
    3 => 0.0,
    4 => "",
    5 => "0",
    6 => "0.0",
    7 => "abc"
];

$return = array_filter($array);

print_r($return);

Array
(
    [6] => 0.0
    [7] => abc
)

2 · callback · true

<?

function myfunction($value)
{
    return $value;
}

$array =
[
    0 => null,
    1 => false,
    2 => 0,
    3 => 0.0,
    4 => "",
    5 => "0",
    6 => "0.0",
    7 => "abc"
];
$callback = "myfunction";

$return = array_filter($array, $callback);

print_r($return);

Array
(
    [6] => 0.0
    [7] => abc
)

3 · callback · strlen

<?

$array =
[
    0 => null,
    1 => false,
    2 => 0,
    3 => 0.0,
    4 => "",
    5 => "0",
    6 => "0.0",
    7 => "abc"
];
$callback = "strlen";

$return = array_filter($array, $callback);

print_r($return);

Array
(
    [2] => 0
    [3] => 0
    [5] => 0
    [6] => 0.0
    [7] => abc
)

4 · callback · even

<?

function myfunction($value)
{
    return !($value & 1);
}

$array =
[
    "a" => 0,
    "b" => 1,
    "c" => 2,
    "d" => 3,
    "e" => 4
];
$callback = "myfunction";

$return = array_filter($array, $callback);

print_r($return);

Array
(
    [a] => 0
    [c] => 2
    [e] => 4
)

5 · callback · odd

<?

function myfunction($value)
{
    return $value & 1;
}

$array =
[
    "a" => 0,
    "b" => 1,
    "c" => 2,
    "d" => 3,
    "e" => 4
];
$callback = "myfunction";

$return = array_filter($array, $callback);

print_r($return);

Array
(
    [b] => 1
    [d] => 3
)

6 · mode · 0

<?

function myfunction($value)
{
    return $value == 4;
}

$array =
[
    "a" => 0,
    "b" => 1,
    "c" => 2,
    "d" => 3,
    "e" => 4
];
$callback = "myfunction";
$mode = 0;

$return = array_filter($array, $callback, $mode);

print_r($return);

Array
(
    [e] => 4
)

7 · mode · ARRAY_FILTER_USE_KEY

<?

function myfunction($key)
{
    return $key == "c";
}

$array =
[
    "a" => 0,
    "b" => 1,
    "c" => 2,
    "d" => 3,
    "e" => 4
];
$callback = "myfunction";
$mode = ARRAY_FILTER_USE_KEY;

$return = array_filter($array, $callback, $mode);

print_r($return);

Array
(
    [c] => 2
)

8 · mode · ARRAY_FILTER_USE_BOTH

<?

function myfunction($value, $key)
{
    return $value == 4 || $key == "c";
}

$array =
[
    "a" => 0,
    "b" => 1,
    "c" => 2,
    "d" => 3,
    "e" => 4
];
$callback = "myfunction";
$mode = ARRAY_FILTER_USE_BOTH;

$return = array_filter($array, $callback, $mode);

print_r($return);

Array
(
    [c] => 2
    [e] => 4
)