(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.
arrayThe array to iterate over
callbackThe callback function to use
If no callback is supplied, all entries of
array equal to FALSE (see
converting to
boolean) will be removed.
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
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 = array("a"=>1, "b"=>2, "c"=>3, "d"=>4, "e"=>5);
$array2 = array(6, 7, 8, 9, 10, 11, 12);
echo "Odd :\n";
print_r(array_filter($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
$entry = array(
0 => 'foo',
1 => false,
2 => -1,
3 => null,
4 => ''
);
print_r(array_filter($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.