array_find_key

(PHP 8 >= 8.4.0)

array_find_key — Returns the key of the first element satisfying a callback function

Description

array_find_key(array $array, callable $callback): mixed

array_find_key() returns the key of the first element of an array for which the given callback returns true . If no matching element is found the function returns null .

Parameters

array

The array that should be searched.

callback

The callback function to call to check each element, which must be

callback(mixed $value, mixed $key): bool

If this function returns true , the key is returned from array_find_key() and the callback will not be called for further elements.

Return Values

The function returns the key of the first element for which the callback returns true . If no matching element is found the function returns null .

Examples

Example #1 array_find_key() example

<?php
$array = [
 'a' => 'dog',
 'b' => 'cat',
 'c' => 'cow',
 'd' => 'duck',
 'e' => 'goose',
 'f' => 'elephant'
];

// Find the first animal with a name longer than 4 characters.
var_dump(array_find_key($array, function (string $value) {
 return strlen($value) > 4;
}));

// Find the first animal whose name begins with f.
var_dump(array_find_key($array, function (string $value) {
 return str_starts_with($value, 'f');
}));

// Find the first animal where the array key is the first symbol of the animal.
var_dump(array_find_key($array, function (string $value, $key) {
 return $value[0] === $key;
}));

// Find the first animal where the array key matching a RegEx.
var_dump(array_find_key($array, function ($value, $key) {
 return preg_match('/^([a-f])$/', $key);
}));
?>

The above example will output:

string(1) "e"
NULL
string(1) "c"
string(1) "a"

Found A Problem?

Learn How To Improve This Page • Submit a Pull Request • Report a Bug

+add a note

User Contributed Notes

There are no user contributed notes for this page.