array_filter | Functions | PHP

Filters elements of an array using a callback function

Syntax

array_filter ( array $array [, callable $callback [, int $flag = 0 ]] ) : array

Parameters

array

The array to iterate over.

callback

The callback function to use. If no callback is supplied, all entries of array equal to FALSE will be removed.

flag

Flag determining what arguments are sent to callback:

0	pass value as the only argument to callback
ARRAY_FILTER_USE_KEY	pass key as the only argument to callback
ARRAY_FILTER_USE_BOTH	pass both value and key as arguments to callback

Return

Returns the filtered array.

Examples

array

<?

$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
)

callback | True

<?

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

$array = 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
)

callback | Even

<?

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

$array = 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
)

flag | 0

<?

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

$array = array(
    "a" => 0,
    "b" => 1,
    "c" => 2,
    "d" => 3,
    "e" => 4
);
$callback = "myfunction";
$flag = 0;

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

var_dump($return);

?>

array(1) {
  ["e"]=>
  int(4)
}

flag | ARRAY_FILTER_USE_KEY

<?

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

$array = array(
    "a" => 0,
    "b" => 1,
    "c" => 2,
    "d" => 3,
    "e" => 4
);
$callback = "myfunction";
$flag = ARRAY_FILTER_USE_KEY;

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

var_dump($return);

?>

array(1) {
  ["c"]=>
  int(2)
}

flag | ARRAY_FILTER_USE_BOTH

<?

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

$array = array(
    "a" => 0,
    "b" => 1,
    "c" => 2,
    "d" => 3,
    "e" => 4
);
$callback = "myfunction";
$flag = ARRAY_FILTER_USE_BOTH;

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

var_dump($return);

?>

array(2) {
  ["c"]=>
  int(2)
  ["e"]=>
  int(4)
}

Links

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