C++ named requirements: ReversibleContainer

A ReversibleContainer is a Container that has iterators that meet the requirements of either LegacyBidirectionalIterator or LegacyRandomAccessIterator. Such iterators allow a ReversibleContainer to be iterated over in reverse.

Requirements

`X`	Container type
`T`	Element type
a	Objects of type `X`

Types

Expression	Return type	Conditions
X::reverse_iterator	Iterator type whose value type is `T`	reverse_iterator<iterator>
X::const_reverse_iterator	Constant iterator type whose value type is `T`	reverse_iterator<const_iterator>

Member functions

Expression	Return type	Conditions	Complexity
a.rbegin()	reverse_iterator; const_reverse_iterator for constant a	reverse_iterator(end())	Constant
a.rend()	reverse_iterator; const_reverse_iterator for constant a	reverse_iterator(begin())	Constant
a.crbegin()	const_reverse_iterator	const_cast<X const&>(a).rbegin()	Constant
a.crend()	const_reverse_iterator	const_cast<X const&>(a).rend()	Constant

Standard library

Example

The following example iterates over a vector (which has random-access iterators) in reverse.

Run this code

#include <iostream>
#include <vector>
 
int main()
{
    std::vector<int> v = {3, 1, 4, 1, 5, 9};
 
    for (std::vector<int>::const_reverse_iterator i{v.crbegin()}; i != v.crend(); ++i)
        std::cout << *i << ' ';
    std::cout << '\n';
}

Output:

9 5 1 4 1 3