PHP array_find_key() Function
Quick summary: The PHP array_find_key() function returns the key of the first element that satisfies a given callback.
PHP array_find_key() Syntax
array_find_key(array $array, callable $callback): mixedPHP
PHP array_find_key() Basic examples
$numbers = [10, 20, 30];
$key = array_find_key($numbers, fn($v)=>$v===20);
var_dump($key);PHP
Output:
int(1)Returns the key of the first matching element.
PHP array_find_key() Real-world usage
$users = ['john'=>25,'jane'=>30];
$key = array_find_key($users, fn($age)=>$age>28);
var_dump($key);PHP
Output:
string(4) "jane"Find user key by condition.
PHP array_find_key() Edge cases
$key = array_find_key([1,2,3], fn($v)=>$v>10);
var_dump($key);PHP
Output:
NULLReturns null if no match found.
PHP array_find_key() Common mistakes
Confusing with array_search()
array_search() searches by value directly.
Incorrect
array_search(fn($v)=>$v>5, $arr);Correct
array_find_key($arr, fn($v)=>$v>5);Use array_find_key() with callback condition.
PHP array_find_key() Frequently Asked Questions
What does array_find_key() do?
Finds key of first matching element using a callback.
Use case?
Finding keys dynamically.
Callback required?
Yes.
Return value?
Key or null.
Common mistake?
Expecting value.
Performance?
Depends on size.
Alternative?
array_search().
Stops early?
Yes.
Safe?
Yes.
Handles objects?
Yes.
Best practice?
Use strict checks.
Used in mapping?
Yes.