# std::experimental::ranges::iterator_category

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< cpp‎ | experimental‎ | ranges

Defined in header `<experimental/ranges/iterator>` |  |
template< class I > struct iterator_category { }; | (1) |
template< class T > struct iterator_category<T*>; | (2) |
template< class T > struct iterator_category<const T> : iterator_category<T> { }; | (3) |
template <class T> requires requires { typename T::iterator_category; } struct iterator_category<T>; | (4) |

Computes the iterator category of the class `I`, if any. Users may specialize `iterator_category` for a program-defined type.

1) Primary template is an empty struct.
2) Specialization for pointers. If `T` is an object type, provides a member type `type` equal to ranges::random_access_iterator_tag. Otherwise, there is no member `type`.
3) Specialization for const-qualified types.
4) Specialization for types that define a public and accessible member type `iterator_category`. If `T::iterator_category` is the same as or derived from one of iterator category tags in namespace `std`, it is mapped to the corresponding tag in the namespace `ranges` as described below. Otherwise, provides a member type `type` equal to `T::iterator_category`.

- If `T::iterator_category` is the same as or derives from std::random_access_iterator_tag, provides a member type `type` equal to ranges::random_access_iterator_tag.
- Otherwise, if `T::iterator_category` is the same as or derives from std::bidirectional_iterator_tag, provides a member type `type` equal to ranges::bidirectional_iterator_tag.
- Otherwise, if `T::iterator_category` is the same as or derives from std::forward_iterator_tag, provides a member type `type` equal to ranges::forward_iterator_tag.
- Otherwise, if `T::iterator_category` is the same as or derives from std::input_iterator_tag, provides a member type `type` equal to ranges::input_iterator_tag.
- Otherwise, if `T::iterator_category` is the same as or derives from std::output_iterator_tag, there is no member `type`.

### Helper alias template

template< class T > using iterator_category_t = typename ranges::iterator_category<T>::type; |  | (ranges TS)

### Example

| This section is incomplete Reason: no example

### See also

input_iterator_tagoutput_iterator_tagforward_iterator_tagbidirectional_iterator_tagrandom_access_iterator_tagcontiguous_iterator_tag (C++20) | empty class types used to indicate iterator categories (class)
input_iterator_tagoutput_iterator_tagforward_iterator_tagbidirectional_iterator_tagrandom_access_iterator_tag | empty class types used to indicate iterator categories (class)
iterator_traits | compatibility traits class that collects an iterator’s associated types (alias template)

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