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operator+(std::reverse_iterator) - cppreference.com

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Defined in header <iterator>

template< class Iter > reverse_iterator<Iter> operator+ ( typename reverse_iterator<Iter>::difference_type n, const reverse_iterator<Iter>& it );

 (constexpr since C++17)
(until C++23)

template< class Iter > constexpr reverse_iterator<Iter> operator+ ( std::iter_difference_t<Iter> n, const reverse_iterator<Iter>& it );

 (since C++23)

Returns the iterator it incremented by n. In fact, the underlying iterator is decremented by n.

Parameters

n - the number of positions to increment the iterator
it - the iterator adaptor to increment

Return value

reverse_iterator<Iter>(it.base() - n)

Example

#include <iostream>
#include <iterator>
#include <list>
#include <vector>

int main()
{
    {
        std::vector v{0, 1, 2, 3};
        std::reverse_iterator<std::vector<int>::iterator>
            ri1{std::reverse_iterator{v.rbegin()}};
        std::cout << *ri1 << ' '; // 3
        std::reverse_iterator<std::vector<int>::iterator> ri2{2 + ri1};
        std::cout << *ri2 << ' '; // 1
    }
    
    {
        std::list l{5, 6, 7, 8};
        std::reverse_iterator<std::list<int>::iterator>
            ri1{std::reverse_iterator{l.rbegin()}};
        std::cout << *ri1 << '\n'; // 8
    //  auto ri2{2 + ri1}; // Error: the underlying iterator does not
                           //        model random access iterator
    }
}

Output:

See also