array_filter
array_filter
(PHP 4 >= 4.0.6, PHP 5, PHP 7)
array_filter — Filters elements of an array using a callback function
Description
array array_filter ( array $array [, callable $callback [, int $flag = 0 ]] )
Iterates over each value in the array
passing them to the callback
function. If the callback
function returns true, the current value from array
is returned into the result array. Array keys are preserved.
Parameters
-
array
-
The array to iterate over
-
callback
-
The callback function to use
If no
callback
is supplied, all entries ofarray
equal toFALSE
(see converting to boolean) will be removed. -
flag
-
Flag determining what arguments are sent to
callback
:-
ARRAY_FILTER_USE_KEY
- pass key as the only argument tocallback
instead of the value -
ARRAY_FILTER_USE_BOTH
- pass both value and key as arguments tocallback
instead of the value
-
Return Values
Returns the filtered array.
Changelog
Version | Description |
---|---|
5.6.0 | Added optional flag parameter and constants ARRAY_FILTER_USE_KEY and ARRAY_FILTER_USE_BOTH |
Examples
Example #1 array_filter() example
<?php function odd($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 = 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) }
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
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Licensed under the Creative Commons Attribution License v3.0 or later.
https://secure.php.net/manual/en/function.array-filter.php