< cpp‎ | iterator
Defined in header <iterator>
template< class Iterator >

class reverse_iterator : public std::iterator<
                           typename std::iterator_traits<Iterator>::iterator_category,
                           typename std::iterator_traits<Iterator>::value_type,
                           typename std::iterator_traits<Iterator>::difference_type,
                           typename std::iterator_traits<Iterator>::pointer,

                           typename std::iterator_traits<Iterator>::reference >
(until C++17)
template< class Iterator >
class reverse_iterator;
(since C++17)

std::reverse_iterator is an iterator adaptor that reverses the direction of a given iterator. In other words, when provided with a bidirectional iterator, std::reverse_iterator produces a new iterator that moves from the end to the beginning of the sequence defined by the underlying bidirectional iterator.

For a reverse iterator r constructed from an iterator i, the relationship &*r == &*(i-1) is always true (as long as r is dereferenceable); thus a reverse iterator constructed from a one-past-the-end iterator dereferences to the last element in a sequence.

This is the iterator returned by member functions rbegin() and rend() of the standard library containers.



[edit] Member types

Member type Definition
value_type std::iterator_traits<Iterator>::value_type
difference_type std::iterator_traits<Iterator>::difference_type
pointer std::iterator_traits<Iterator>::pointer
reference std::iterator_traits<Iterator>::reference
iterator_category std::iterator_traits<Iterator>::iterator_category

Note: before C++17, these member types are required to be obtained by inheriting from std::iterator< std::iterator_traits<Iterator>::iterator_category
, std::iterator_traits<Iterator>::value_type
, std::iterator_traits<Iterator>::difference_type
, std::iterator_traits<Iterator>::pointer
, std::iterator_traits<Iterator>::reference

Member type Definition
iterator_type Iterator

[edit] Member functions

constructs a new iterator adaptor
(public member function) [edit]
assigns another iterator
(public member function) [edit]
accesses the underlying iterator
(public member function) [edit]
accesses the pointed-to element
(public member function) [edit]
accesses an element by index
(public member function) [edit]
advances or decrements the iterator
(public member function) [edit]

[edit] Member objects

Member name Definition
current (protected) a copy of the base() iterator

[edit] Non-member functions

compares the underlying iterators
(function template) [edit]
advances the iterator
(function template) [edit]
computes the distance between two iterator adaptors
(function template) [edit]

[edit] Example

#include <iostream>
#include <string>
#include <iterator>
int main()
    std::string s = "Hello, world";
    std::reverse_iterator<std::string::iterator> r = s.rbegin();
    r[7] = 'O'; // replaces 'o' with 'O' 
    r += 7; // iterator now points at 'O'
    std::string rev(r, s.rend());
    std::cout << rev << '\n';



[edit] See also

the basic iterator
(class template) [edit]