array_filter
(PHP 4 >= 4.0.6, PHP 5, PHP 7)
array_filter — Filters elements of an array using a callback function
Description
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.
Parameters
-
array -
The array to iterate over
-
callback -
The callback function to use
If no
callbackis supplied, all entries ofarrayequal toFALSE(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 tocallbackinstead of the value -
ARRAY_FILTER_USE_BOTH- pass both value and key as arguments tocallbackinstead of the value
callbackinstead. -
Changelog
| Version | Description |
|---|---|
| 5.6.0 |
Added optional flag parameter and constants
ARRAY_FILTER_USE_KEY and
ARRAY_FILTER_USE_BOTH
|
Examples
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)
}
Notes
If the array is changed from the callback function (e.g. element added, deleted or unset) the behavior of this function is undefined.
See Also
- array_map() - Applies the callback to the elements of the given arrays
- array_reduce() - Iteratively reduce the array to a single value using a callback function
- array_walk() - Apply a user supplied function to every member of an array
English translation
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Document created the 30/01/2003, last modified the 26/10/2018
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References
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