An empty base struct used to ensure that a user-defined iterator class works properly with iterator_traits.
template<class Category, class Type, class Distance = ptrdiff_t
class Pointer = Type*, class Reference = Type&>
struct iterator {
typedef Category iterator_category;
typedef Type value_type;
typedef Distance difference_type;
typedef Distance distance_type;
typedef Pointer pointer;
typedef Reference reference;
};
Remarks
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.
Example
See iterator_traits for an example of how to declare and use the types in the iterator base class.
Requirements
Header: <iterator>
Namespace: std