php - array_key_exists

Description

bool array_key_exists ( mixed $key, array $search )
array_key_exists() returns TRUE if the given key is set in the array. key can be any value possible for an array index. array_key_exists() also works on objects.

Parameters

key

Value to check.

search

An array with keys to check.

Return Values

Returns TRUE on success or FALSE on failure.

Examples

Example 249. array_key_exists() example


$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 250. array_key_exists() vs isset()

isset() does not return TRUE for array keys that correspond to a NULL value, while array_key_exists() does.
 

$search_array = array('first' => null, 'second' => 4);
// returns falseisset($search_array['first']);
// returns truearray_key_exists('first', $search_array);