Опис

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

Applies the user-defined callback function to each element of the array array.

array_walk() is not affected by the internal array pointer of array. array_walk() will walk through the entire array regardless of pointer position.

Параметри

array

The input array.

callback

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

Зауваження:
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.

Зауваження:
Many internal functions (for example strtolower()) will throw if more than the expected number of arguments are passed in and are not usable directly as a callback.

Only the values of the array may potentially be changed; its structure cannot be altered, i.e., the programmer cannot add, unset or reorder elements. If the callback does not respect this requirement, the behavior of this function is undefined, and unpredictable.

arg

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

Значення, що повертаються

Завжди повертає true.

Помилки/виключення

As of PHP 7.1.0, an ArgumentCountError will be thrown if the callback function requires more than 2 parameters (the value and key of the array member), or more than 3 parameters if the arg is also passed. Previously, in this case an error of level E_WARNING would be generated each time array_walk() calls callback.

Журнал змін

Версія	Опис
8.2.0	Тепер повертається значення типу `true`. До цього був bool.
8.0.0	If `callback` expects the second or third parameter to be passed by reference, this function will now emit an `E_WARNING`.

Приклади

Приклад #1 array_walk() example

<?php
$fruits = array("d" => "lemon", "a" => "orange", "b" => "banana", "c" => "apple");

function test_alter(&$item1, $key, $prefix)
{
    $item1 = "$prefix: $item1";
}

function test_print($item2, $key)
{
    echo "$key. $item2\n";
}

echo "Before ...:\n";
array_walk($fruits, 'test_print');

array_walk($fruits, 'test_alter', 'fruit');
echo "... and after:\n";

array_walk($fruits, 'test_print');
?>

Поданий вище приклад виведе:

Before ...:
d. lemon
a. orange
b. banana
c. apple
... and after:
d. fruit: lemon
a. fruit: orange
b. fruit: banana
c. fruit: apple

Приклад #2 array_walk() example using anonymous function

<?php
$elements = ['a', 'b', 'c'];

array_walk($elements, function ($value, $key) {
  echo "{$key} => {$value}\n";
});

?>

Поданий вище приклад виведе:

0 => a
1 => b
2 => c

Прогляньте також

array_walk_recursive() - Apply a user function recursively to every member of an array
iterator_apply() - Call a function for every element in an iterator
list() - Assign variables as if they were an array
each() - Return the current key and value pair from an array and advance the array cursor
call_user_func_array() - Call a callback with an array of parameters
array_map() - Застосовує зворотній виклик до всіх елементів зазначених масивів
foreach