An empty base struct used to ensure that a user-defined iterator class works properly with iterator_traits.

struct iterator {
   typedef Category iterator_category;
   typedef Type value_type;
   typedef Distance difference_type;
   typedef Distance distance_type;
   typedef Pointer pointer;
   typedef Reference reference;
   };

The template struct serves as a base type for all iterators. It defines the member types

• iterator_category (a synonym for the template parameter Category).

• value_type (a synonym for the template parameter Type).

• difference_type (a synonym for the template parameter Distance).

• distance_type (a synonym for the template parameter Distance)

• pointer (a synonym for the template parameter Pointer).

• reference (a synonym for the template parameter Reference).

Note that value_type should not be a constant type even if pointer points at an object of const Type and reference designates an object of const Type.

See iterator_traits for an example of how to declare and use the types in the iterator base class.

Header: <iterator>

Namespace: std

<iterator>
Thread Safety in the C++ Standard Library
C++ Standard Library Reference