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 | complexity |
|---|---|---|---|
X::reverse_iterator |
iterator type whose value type is T |
reverse_iterator<iterator> |
compile time |
X::const_reverse_iterator |
constant iterator type whose value type is T |
reverse_iterator<const_iterator> |
compile time |
Methods
| 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.
#include <vector>
#include <iostream>
int main()
{
std::vector<int> v = {3, 1, 4, 1, 5, 9};
for(std::vector<int>::reverse_iterator i = v.rbegin(); i != v.rend(); ++i) {
std::cout << *i << ' ';
}
}
Output:
9 5 1 4 1 3
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https://en.cppreference.com/w/cpp/named_req/ReversibleContainer
