PHP Manual . Prev . Next . PHP 4 >= 4.1.0) array_key_exists -- Checks if the given key or index exists in the array . 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. Example 1. 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"; } . ...