std::counted_iterator<I>::base

#include <algorithm>
#include <iostream>
#include <iterator>
#include <type_traits>
#include <vector>

int main()
{
    std::vector<int> v{0, 1, 2, 3, 4};

    std::reverse_iterator<std::vector<int>::iterator> reverse{v.rbegin()};

    std::counted_iterator counted{reverse, 3};

    static_assert(std::is_same<
        decltype(counted.base()),
        std::reverse_iterator<std::vector<int>::iterator> const&
    >{});

    std::cout << "Print with reverse_iterator: ";
    for (auto r = counted.base(); r != v.rend(); ++r)
        std::cout << *r << ' ';
    std::cout << '\n';

    std::cout << "Print with counted_iterator: ";
    for (; counted != std::default_sentinel; ++counted)
        std::cout << counted[0] << ' ';
    std::cout << '\n';
}

Вывод:

Print with reverse_iterator: 4 3 2 1 0
Print with counted_iterator: 4 3 2