(PHP 4 >= 4.0.7, PHP 5)
array_key_exists — Checks if the given key or index exists in the array
array_key_exists() returns TRUE if the given key is set in the array. key can be any value possible for an array index.
Value to check.
An array with keys to check.
Returns TRUE on success or FALSE on failure.
| Version | Description |
|---|---|
| 5.3.0 | This function doesn't work with objects anymore, property_exists() should be used in this case. |
Example #1 array_key_exists() example
<?php
$search_array = array('first' => 1, 'second' => 4);
if (array_key_exists('first', $search_array)) {
echo "The 'first' element is in the array";
}
?>
Note: The name of this function is key_exists() in PHP 4.0.6.
Example #2 array_key_exists() vs isset()
isset() does not return TRUE for array keys that correspond to a NULL value, while array_key_exists() does.
<?php
$search_array = array('first' => null, 'second' => 4);
// returns false
isset($search_array['first']);
// returns true
array_key_exists('first', $search_array);
?>