array_key_exists()¶
array_key_exists() reports if a key has been assigned any value in an array. It reports true if it is, and false otherwise.
array_key_exists() is often compared to isset(), although they have differences: array_key_exists() returns true as long as the index exists, while isset() also checks the corresponding value for not being null.
Unlike its name, array_key_exists() works on array as well as objects. This is a deprecated feature, since PHP 8.0.
<?php
$array = ['a' => 1, 2, 3 => 3, 4 => null];
var_dump(array_key_exists('a' , $array)); // true
var_dump(array_key_exists(1 , $array)); // false (0 => 2)
var_dump(array_key_exists('3' , $array)); // true
var_dump(array_key_exists(4 , $array)); // true
var_dump(array_key_exists('abc', $array)); // false
?>
See also isset() vs array_key_exists().
Related : Isset
