PHP 8.4: New Array Functions

PHP 8.4 introduces four new array functions that make use of callback functions for searching and inspecting array elements: array_find, array_find_key, array_all, and array_any.

These functions simplify common operations such as finding array elements that match specific criteria (checked using a callback function) and verifying if any or all elements in an array meet a certain condition.

The array_find Function

The array_find function returns the value of the first array element for which the callback returns true. If no elements match the condition, the function returns null.

Function Synopsis

/**
 * Returns the VALUE of the first element from $array for which the
 *  $callback returns true. Returns null if no matching element is
 *  found.
 *
 * @param array $array The array to be searched.
 * @param callable $callback The callback function to check
 *  each element. The first parameter contains the value ($value),
 *  the second parameter contains the corresponding key ($key).
 *  If this callback returns true (or a truthy value), the value
 *  ($value) is returned immediately, and the callback will not be
 *  called for further elements.
 *
 * @return mixed The function returns the value of the first
 *  element for which the $callback returns true. null, if no
 *  matching element is found. Note that the matching element value
 *  itself could be null as well.
 */
function array_find(array $array, callable $callback): mixed {}

Usage Examples

function is_even(int $value): bool {
    return $value % 2 === 0;
}
echo array_find([1, 2, 3, 4, 5], 'is_even'); // Output: 2

echo array_find([1, 2, 3, 4, 5], fn($value) => $value % 2 === 0); // Output: 2

function is_key_numeric(mixed $value, mixed $key): bool {
    return is_numeric($key);
}
echo array_find(['a' => 'foo', 2 => 'bar'], 'is_key_numeric'); // Output: "bar"

The array_find_key Function

The array_find_key function is similar to array_find, but it returns the key of the first array element for which the callback returns true. If no elements match the condition, the function returns null.

Function Synopsis

/**
 * Returns the KEY of the first element from $array for which the
 *  $callback returns true. If no matching element is found, the
 *  function returns null.
 *
 * @param array $array The array to be searched.
 * @param callable $callback The callback function to check
 *  each element. The first parameter contains the value ($value),
 *  the second parameter contains the corresponding key ($key). If
 *  this function returns true, the key ($key) is returned
 *  immediately, and the callback will not be called for further
 *  elements.
 *
 * @return mixed The key of the first element for which the
 *  $callback returns true. null, if no matching element is found.
 */
function array_find_key(array $array, callable $callback): mixed {}

Usage Examples

function is_even(int $value): bool {
    return $value % 2 === 0;
}
echo array_find_key(['foo' => 1, 'bar' => 2, 'baz' => 3], 'is_even'); // Output: "bar"

echo array_find_key(
    ['foo' => 1, 'bar' => 2, 'baz' => 3],
    fn($value) => $value % 2 === 0
); // Output: "bar"

function is_key_numeric(mixed $value, mixed $key): bool {
    return is_numeric($key);
}
echo array_find_key(['a' => 'foo', 2 => 'bar'], 'is_key_numeric'); // Output: "2"

The array_all Function

The array_all function takes an array and a callback, and returns true if all elements in the array return true when passed to the callback. The callback function is called with the value ($value) and key ($key) of each element in the array. array_all returns true for empty arrays ([]).

Function Synopsis

/**
 * Checks whether the $callback returns true for all the array
 *  elements.
 *
 * @param array $array The array to be searched.
 * @param callable $callback The callback function to check
 *  each element. The first parameter contains the value ($value), the
 *  second parameter contains the corresponding key ($key). If this function
 *  returns false (or any falsy value), false is returned immediately,
 *  and the $callback will not be called for further elements.
 *
 * @return bool true, if $callback returns true for all elements.
 *  false otherwise.
 */
function array_all(array $array, callable $callback): bool {}

Usage Examples

echo array_all(
    ['foo@example.com', 'bar@example.com', 'baz@example.com'],
    fn($value) => filter_var($value, FILTER_VALIDATE_EMAIL)
); // Output: true

echo array_all(
    ['foo@example.com', 'bar@example.com', 'baz'],
    fn($value) => filter_var($value, FILTER_VALIDATE_EMAIL)
); // Output: false

echo array_all(
    [1 => '', 2 => '', 3 => ''],
    fn($value, $key) => is_numeric($key)
); // Output: true

The array_any Function

The array_any function is similar to array_all. It takes an array and a callback, and returns true if any element in the array returns true when passed to the callback. The callback function is called with the value ($value) and key ($key) of each element in the array. Once the first element returns true from the callback, the callback is not called on the remaining elements. array_any returns false for empty arrays ([]).

Function Synopsis

 * Checks whether the $callback returns true for any of the array
 *  elements.
 *
 * @param array $array The array to be searched.
 * @param callable $callback The callback function to check
 *  each element. The first parameter contains the value ($value), the
 *  second parameter contains the corresponding key ($key). If this
 *  function returns true (or a truthy value), true is returned
 *  immediately, and the $callback will not be called for further
 *  elements.
 *
 * @return bool true if there is at least one element for which
 *  $callback returns true. false otherwise.
 */
function array_any(array $array, callable $callback): bool {}

Usage Examples

echo array_any(
    ['foo@example.com', 'https://keeplearning.dev', 'foobar'],
    fn($value) => filter_var($value, FILTER_VALIDATE_URL)
); // Output: true

echo array_all(
    ['https://keeplearning.dev', new stdClass()],
    fn($value) => filter_var($value, FILTER_VALIDATE_EMAIL)
); // Output: false

echo array_any(
    [1 => '', 'bar' => '', 'baz' => ''],
    fn($value, $key) => is_numeric($key)
); // Output: true