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std::reverse_iterator<Iter>::base

iterator_type base() const;
 (until C++17) 
constexpr iterator_type base() const;
 (since C++17)

Returns the underlying base iterator. That is std::reverse_iterator(it).base() == it.

The base iterator refers to the element that is next (from the std::reverse_iterator::iterator_type perspective) to the element the reverse_iterator is currently pointing to. That is &*(rit.base() - 1) == &*rit.

Parameters

(none).

Return value

The underlying iterator.

Exceptions

May throw implementation-defined exceptions.

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';
}

Output:

*it == 3
*r_it == 2
*r_it.base() == 3
*(r_it.base()-1) == 2
0 1 2 3 4 5
5 4 3 2 1 0

See also

accesses the pointed-to element
(public member function)

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