std::reverse_iterator

 

C++

Language

Standard library headers

Concepts

Utilities library

Strings library

Containers library

Algorithms library

Iterators library

Numerics library

Input/output library

Localizations library

Regular expressions library (C++11)

Atomic operations library (C++11)

Thread support library (C++11)

Technical Specifications

 

Iterator library

Iterator primitives
iterator_traits
input_iterator_tagoutput_iterator_tagforward_iterator_tagbidirectional_iterator_tagrandom_access_iterator_tag
iterator
Iterator adaptors
reverse_iterator move_iterator (C++11) back_insert_iterator front_insert_iterator insert_iterator	make_reverse_iterator (C++14) make_move_iterator (C++11) back_inserter front_inserter inserter
Stream iterators
istream_iterator
ostream_iterator
istreambuf_iterator
ostreambuf_iterator
Iterator operations
advance
distance
prev (C++11)
next (C++11)
Range access
begincbegin (C++11)(C++14)
endcend (C++11)(C++14)
rbegincrbegin (C++14)(C++14)
rendcrend (C++14)(C++14)
Container access
size (C++17)
empty (C++17)
data (C++17)

 

std::reverse_iterator

Member functions

reverse_iterator::reverse_iterator

reverse_iterator::operator=

reverse_iterator::base

reverse_iterator::operator*reverse_iterator::operator->

reverse_iterator::operator[]

reverse_iterator::operator++reverse_iterator::operator+reverse_iterator::operator+=reverse_iterator::operator--reverse_iterator::operator-reverse_iterator::operator-=

Non-member functions

operator==operator!=operator<operator>

operator+

operator-

 

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.

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

Member functions

(constructor)	constructs a new iterator adaptor (public member function)
operator=	assigns another iterator (public member function)
base	accesses the underlying iterator (public member function)
operator*operator->	accesses the pointed-to element (public member function)
operator[]	accesses an element by index (public member function)
operator++operator++(int)operator+=operator+operator--operator--(int)operator-=operator-	advances or decrements the iterator (public member function)

Member objects

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

Non-member functions

operator==operator!=operator<operator<=operator>operator>=	compares the underlying iterators (function template)
operator+	advances the iterator (function template)
operator-	computes the distance between two iterator adaptors (function template)

Example

Run this code

#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';
}

Output:

OlleH

See also

iterator

the basic iterator (class template)