Checks if the given key or index exists in the array array_intersect array_keys Array Functions PHP Manual array_key_exists (PHP 4 >= 4.0.7, PHP 5)array_key_exists — Checks if the given key or index exists in the array Description bool array_key_exists ( mixed $key , array $search ) array_key_exists() returns TRUE if the given key is set in the array. key can be any value possible for an array index. Parameters key Value to check. search An array with keys to check. Return Values Returns TRUE on success or FALSE on failure. ChangeLog Version Description 5.3.0 This function doesn't work with objetcs anymore, property_exists() should be used in this case. Examples Example #1 array_key_exists() example <?php$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 falseisset($search_array['first']);// returns truearray_key_exists('first', $search_array);?> See Also isset() array_keys() in_array() property_exists() array_intersect array_keys Array Functions PHP Manual
