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array_walk_recursive

Description

The array_walk_recursive of Array for PHP applies a user function recursively to every member of an array.

Syntax

array_walk_recursive(
    array|object &$array,
    callable $callback,
    mixed $arg = null
): true

Parameters

array

The input array.

callback

Typically, callback takes on two parameters. The array parameter's value being the first, and the key/index second.

NOTE: If callback needs to be working with the actual values of the array, specify the first parameter of callback as a reference. Then, any changes made to those elements will be made in the original array itself.

arg

If the optional arg parameter is supplied, it will be passed as the third parameter to the callback.

Return

Returns true.

Examples

1 · array callback

<?

function callback(&$value, $key)
{
    return $value .= " pie";
}

$array =
[
    "a" =>
    [
        "cherry",
        "pumpkin"
    ],
    "b" => "banana",
    "c" => "apple",
    "d" => "lemon"
];
$callback = "callback";

array_walk_recursive($array, $callback);

print_r($array);

Array
(
    [a] => Array
        (
            [0] => cherry pie
            [1] => pumpkin pie
        )

    [b] => banana pie
    [c] => apple pie
    [d] => lemon pie
)

2 · arg

<?

function callback(&$value, $key, $arg)
{
    return $value = "$arg: $value pie";
}

$array =
[
    "a" =>
    [
        "cherry",
        "pumpkin"
    ],
    "b" => "banana",
    "c" => "apple",
    "d" => "lemon"
];
$callback = "callback";
$arg = "dessert";

array_walk_recursive($array, $callback, $arg);

print_r($array);

Array
(
    [a] => Array
        (
            [0] => dessert: cherry pie
            [1] => dessert: pumpkin pie
        )

    [b] => dessert: banana pie
    [c] => dessert: apple pie
    [d] => dessert: lemon pie
)