std::reverse_iterator
| Defined in header <iterator>
|
||
| template< class Iter > class reverse_iterator : public std::iterator< |
(until C++17) | |
| template< class Iter > 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<Iter>::value_type |
difference_type
|
std::iterator_traits<Iter>::difference_type |
pointer
|
std::iterator_traits<Iter>::pointer |
reference
|
std::iterator_traits<Iter>::reference |
iterator_category
|
std::iterator_traits<Iter>::iterator_category |
|
These member types are required to be obtained by inheriting from std::iterator< std::iterator_traits<Iter>::iterator_category |
(until C++17) |
| Member type | Definition |
iterator_type
|
Iter
|
Member functions
| constructs a new iterator adaptor (public member function) | |
| assigns another iterator (public member function) | |
| accesses the underlying iterator (public member function) | |
| accesses the pointed-to element (public member function) | |
| accesses an element by index (public member function) | |
| advances or decrements the iterator (public member function) |
Member objects
| Member name | Definition |
current (protected)
|
a copy of the base() iterator |
Non-member functions
| (C++14) |
creates a std::reverse_iterator of type inferred from the argument (function template) |
| compares the underlying iterators (function template) | |
| advances the iterator (function template) | |
| computes the distance between two iterator adaptors (function template) |
Notes
std::reverse_iterator does not work with iterators that return a reference to a member object (so-called "stashing iterators"). An example of stashing iterator is std::filesystem::path::iterator.
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'; }
Output:
OlleH
See also
| (deprecated in C++17) |
base class to ease the definition of required types for simple iterators (class template) |