C++ named requirements: ReversibleContainer
From cppreference.com
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 |
Example
The following example iterates over a vector (which has random-access iterators) in reverse.
Run this code
#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 << '\n'; } }
Output:
9 5 1 4 1 3