C++ named requirements: ReversibleContainer

 

C++

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Standard library headers

Named requirements

Feature test macros (C++20)

Language support library

Concepts library (C++20)

Metaprogramming library (C++11)

Diagnostics library

General utilities library

Strings library

Containers library

Iterators library

Ranges library (C++20)

Algorithms library

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Filesystem library (C++17)

Regular expressions library (C++11)

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Technical specifications

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External libraries

 

C++ named requirements

Basic DefaultConstructible MoveConstructible (C++11) CopyConstructible CopyAssignable MoveAssignable (C++11) Destructible Type properties ScalarType PODType TriviallyCopyable (C++11) TrivialType (C++11) StandardLayoutType (C++11)   ImplicitLifetimeType Library-wide BooleanTestable EqualityComparable LessThanComparable Swappable ValueSwappable (C++11) NullablePointer (C++11) Hash (C++11) Allocator FunctionObject Callable Predicate BinaryPredicate Compare

Container Container ReversibleContainer AllocatorAwareContainer SequenceContainer ContiguousContainer (C++17) AssociativeContainer UnorderedAssociativeContainer (C++11)   Container element DefaultInsertable (C++11) CopyInsertable (C++11) MoveInsertable (C++11) EmplaceConstructible (C++11) Erasable (C++11) Iterator LegacyIterator LegacyInputIterator LegacyOutputIterator LegacyForwardIterator LegacyBidirectionalIterator LegacyRandomAccessIterator LegacyContiguousIterator (C++17) ConstexprIterator (C++20) Stream I/O FormattedInputFunction UnformattedInputFunction FormattedOutputFunction UnformattedOutputFunction Formatters BasicFormatter (C++20) Formatter (C++20)

Random Numbers SeedSequence (C++11) RandomNumberEngine (C++11) RandomNumberDistribution (C++11) UniformRandomBitGenerator (C++11) RandomNumberEngineAdaptor (C++11) Concurrency BasicLockable (C++11) Lockable (C++11) TimedLockable (C++11) SharedLockable (C++14) SharedTimedLockable (C++14) Mutex (C++11) TimedMutex (C++11) SharedMutex (C++17) SharedTimedMutex (C++14) Ranges RangeAdaptorObject (C++20) RangeAdaptorClosureObject (C++20) Multidimensional View LayoutMapping (C++23) LayoutMappingPolicy (C++23) AccessorPolicy (C++23) Other CharTraits RegexTraits (C++11)   BitmaskType LiteralType (C++11) NumericType UnaryTypeTrait (C++11) BinaryTypeTrait (C++11) TransformationTrait (C++11) Clock (C++11) TrivialClock (C++11)

 

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

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

• std::array
• std::deque
• std::list
• std::vector
• std::map
• std::multimap
• std::set
• std::multiset

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>::reverse_iterator i = v.rbegin(); i != v.rend(); ++i)
        std::cout << *i << ' ';
    std::cout << '\n';
}

Output:

9 5 1 4 1 3