std::iterator_traits<std::counted_iterator>

Inherits the properties from customized (generated from either a standard partial specialization or a program-defined specialization) std::iterator_traits<I> , with the member type pointer adjusted, where I models input_iterator

Notably, the iterator_concept (if present) and iterator_category are inherited from std::iterator_traits<I>

The condition in the requires-clause is true if and only if std::iterator_traits<I>

Note

Before P2259R1, this specialization is used even if std::iterator_traits<I> is generated from the primary template. As a result, when testing std::counted_iterator<I> against an iterator concept (e.g. forward_iterator), the determination of /*ITER_CONCEPT*/ does not take I::iterator_concept into account, and thus std::counted_iterator<I>

The standard library provides partial specializations of std::iterator_traits for pointer types, std::counted_iterator, and std::common_iterator

Example

#include <iterator>
#include <list>
#include <type_traits>
#include <vector>
 
int main()
{
    std::vector v{1, 2, 3, 4};
    std::list l{1, 2, 3, 4};
    std::counted_iterator iv{v.begin(), 3};
    std::counted_iterator il{l.begin(), 3};
    static_assert(std::is_same<int*, std::iterator_traits<decltype(iv)>::pointer>());
    static_assert(std::is_same<void, std::iterator_traits<decltype(il)>::pointer>());
}

Defect reports

The following behavior-changing defect reports were applied retroactively to previously published C++ standards.

See also