(PHP 4 >= 4.0.6, PHP 5, PHP 7)
array_filter — Filters elements of an array using a callback function
array_filter ( array $array [, callable|null $callback = null [, int $mode = 0 ]] ) : array
Iterates over each value in the array passing them to the callback function. If the callback function returns true, the current value from array is returned into the result array.
Array keys are preserved, and may result in gaps if the array was indexed. The result array can be reindexed using the array_values() function.
array
The array to iterate over
callback
The callback function to use
If no callback is supplied, all empty entries of array will be removed. See empty() for how PHP defines empty in this case.
mode
Flag determining what arguments are sent to callback:
ARRAY_FILTER_USE_KEY - pass key as the only argument to callback instead of the value ARRAY_FILTER_USE_BOTH - pass both value and key as arguments to callback instead of the value 0 which will pass value as the only argument to callback instead. Returns the filtered array.
| Version | Description |
|---|---|
| 8.0.0 | callback is nullable now. |
| 5.6.0 | Added optional mode parameter and constants ARRAY_FILTER_USE_KEY and ARRAY_FILTER_USE_BOTH |
Example #1 array_filter() example
<?php
function odd($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 mode
<?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.
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Licensed under the Creative Commons Attribution License v3.0 or later.
https://www.php.net/manual/en/function.array-filter.php