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operator+(std::reverse_iterator)

From cppreference.com
 
 
Iterator library
Iterator concepts
Iterator primitives
Algorithm concepts and utilities
Indirect callable concepts
Common algorithm requirements
Utilities
(C++20)
Iterator adaptors
Stream iterators
Iterator customization points
Iterator operations
(C++11)
(C++11)
Range access
(C++11)(C++14)
(C++11)(C++14)
(C++17)(C++20)
(C++14)(C++14)
(C++14)(C++14)
(C++17)
(C++17)
 
 
template< class Iter >

reverse_iterator<Iter>
    operator+( typename reverse_iterator<Iter>::difference_type n,

               const reverse_iterator<Iter>& it );
(until C++17)
template< class Iter >

constexpr reverse_iterator<Iter>
    operator+( typename reverse_iterator<Iter>::difference_type n,

               const reverse_iterator<Iter>& it );
(since C++17)

Returns the iterator it incremented by n.

Contents

[edit] Parameters

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

[edit] Return value

The incremented iterator, that is reverse_iterator<Iter>(it.base() - n)

[edit] 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 the random access iterator
    }
}

Output:

3 1 8

[edit] See also

advances or decrements the iterator
(public member function) [edit]
computes the distance between two iterator adaptors
(function template) [edit]