(PHP 4 >= 4.0.6, PHP 5, PHP 7)
array_filter — Filters elements of an array using a callback function
Iterates over each value in the array
passing them to the callback function.
If the callback function returns TRUE, the
current value from array is returned into
the result array.
Array keys are preserved, and may result in gaps if the array was indexed.
The result array can be reindexed using the array_values() function.
arrayThe array to iterate over
callbackThe callback function to use
If no callback is supplied, all empty entries of
array will be removed. See empty()
for how PHP defines empty in this case.
flag
Flag determining what arguments are sent to callback:
ARRAY_FILTER_USE_KEY - pass key as the only argument
to callback instead of the value
ARRAY_FILTER_USE_BOTH - pass both value and key as
arguments to callback instead of the value
0 which will pass value as the only argument
to callback instead.
Returns the filtered array.
| Version | Description |
|---|---|
| 5.6.0 |
Added optional flag parameter and constants
ARRAY_FILTER_USE_KEY and
ARRAY_FILTER_USE_BOTH
|
Example #1 array_filter() example
<?php
function odd($var)
{
// returns whether the input integer is odd
return $var & 1;
}
function even($var)
{
// returns whether the input integer is even
return !($var & 1);
}
$array1 = ['a' => 1, 'b' => 2, 'c' => 3, 'd' => 4, 'e' => 5];
$array2 = [6, 7, 8, 9, 10, 11, 12];
echo "Odd :\n";
print_r(array_filter($array1, "odd"));
echo "Even:\n";
print_r(array_filter($array2, "even"));
?>
The above example will output:
Odd :
Array
(
[a] => 1
[c] => 3
[e] => 5
)
Even:
Array
(
[0] => 6
[2] => 8
[4] => 10
[6] => 12
)
Example #2 array_filter() without
callback
<?php
$entry = [
0 => 'foo',
1 => false,
2 => -1,
3 => null,
4 => '',
5 => '0',
6 => 0,
];
print_r(array_filter($entry));
?>
The above example will output:
Array
(
[0] => foo
[2] => -1
)
Example #3 array_filter() with
flag
<?php
$arr = ['a' => 1, 'b' => 2, 'c' => 3, 'd' => 4];
var_dump(array_filter($arr, function($k) {
return $k == 'b';
}, ARRAY_FILTER_USE_KEY));
var_dump(array_filter($arr, function($v, $k) {
return $k == 'b' || $v == 4;
}, ARRAY_FILTER_USE_BOTH));
?>
The above example will output:
array(1) {
["b"]=>
int(2)
}
array(2) {
["b"]=>
int(2)
["d"]=>
int(4)
}
If the array is changed from the callback function (e.g. element added, deleted or unset) the behavior of this function is undefined.