PHP: array_filter function - Filters elements of an array using a callback function

Description

array array_filter ( array $input [, callback $callback ] )

Iterates over each value in the input array passing them to the callback function. If the callback function returns true, the current value from input is returned into the result array. Array keys are preserved.

Parameters

input

The array to iterate over

callback

The callback function to use

If no callback is supplied, all entries of input equal to FALSE (see converting to boolean) will be removed.

Return Values

Returns the filtered array.

Examples

Example #1 array_filter() example


<?php
function odd($var)
{
    return($var & 1);
}

function even($var)
{
    return(!($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
)

Notes

Caution

If the array is changed from the callback function (e.g. element added, deleted or unset) the behavior of this function is undefined.

array_filter

Description

Parameters

Return Values

Examples

Notes

See Also