std::experimental::ranges::input_iterator_tag, std::experimental::ranges::output_iterator_tag, std::experimental::ranges::forward_iterator_tag, std::experimental::ranges::bidirectional_iterator_tag, std::experimental::ranges::random_access_iterator_tag

< cpp‎ | experimental‎ | ranges
Technical specifications
Filesystem library (filesystem TS)
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struct input_iterator_tag { };
struct output_iterator_tag { };
struct forward_iterator_tag : public input_iterator_tag { };
struct bidirectional_iterator_tag : public forward_iterator_tag { };
struct random_access_iterator_tag : public bidirectional_iterator_tag { };

Defines the category of an iterator. Each tag is an empty type and corresponds to one of the five iterator categories:

Iterator category tags carry information that can be used to select the most efficient algorithms for the specific requirement set that is implied by the category. However, concept-based overloading is preferred.

For every InputIterator type I, ranges::iterator_category_t<I> must be defined to be an alias for the most specific category tag that describes the iterator's behavior.


See also

empty class types used to indicate iterator categories
compatibility traits class that collects an iterator’s associated types
(alias template)