If you extend a class and override a method, you must make sure the overridden method has the same "prototype", i.e., it must have the same number of method arguments in the same order. That's why you get the first warning:
Warning: Declaration of tags::index() should be compatible with questions::index($query_where = '', $query_join = '', $called_from = NULL) in C:\xampp\htdocs\myweb\others\tags.php on line 3
Second, if you want to call a function with the same name from the parent class, you'll need to use the parent
keyword:
class tags extends questions {
public function index ($query_where = '', $query_join = '', $called_from = NULL) {
return parent::index($query_where, $query_join, $called_from);
}
}