std::reverse_iterator<Iter>::base
Min standard notice:
Returns the underlying iterator.
# Declarations
iterator_type base() const;
(constexpr since C++17)
# Return value
# Notes
The base iterator refers to the element that is next (from the iterator_type perspective) to the element the reverse_iterator is currently pointing to. That is &(this->base() - 1) == &(*this).
# Example
#include <iostream>
#include <iterator>
#include <vector>
int main()
{
std::vector<int> v = {0, 1, 2, 3, 4, 5};
using RevIt = std::reverse_iterator<std::vector<int>::iterator>;
const auto it = v.begin() + 3;
RevIt r_it{it};
std::cout << "*it == " << *it << '\n'
<< "*r_it == " << *r_it << '\n'
<< "*r_it.base() == " << *r_it.base() << '\n'
<< "*(r_it.base() - 1) == " << *(r_it.base() - 1) << '\n';
RevIt r_end{v.begin()};
RevIt r_begin{v.end()};
for (auto it = r_end.base(); it != r_begin.base(); ++it)
std::cout << *it << ' ';
std::cout << '\n';
for (auto it = r_begin; it != r_end; ++it)
std::cout << *it << ' ';
std::cout << '\n';
}