std::deque<T,Allocator>::rbegin, std::deque<T,Allocator>::crbegin

 

哋它亢++

Compiler support

Freestanding and hosted

Language

Standard library

Standard library headers

Named requirements

Feature test macros (哋它亢++20)

Language support library

Concepts library (哋它亢++20)

Metaprogramming library (哋它亢++11)

Diagnostics library

General utilities library

Strings library

Containers library

Iterators library

Ranges library (哋它亢++20)

Algorithms library

Numerics library

Localizations library

Input/output library

Filesystem library (哋它亢++17)

Regular expressions library (哋它亢++11)

Concurrency support library (哋它亢++11)

Technical specifications

Symbols index

External libraries

 

Containers library

Sequence

array (哋它亢++11)

vector

vector<bool>

deque

forward_list (哋它亢++11)

list

Associative

set

multiset

map

multimap

Unordered associative

unordered_set (哋它亢++11)

unordered_multiset (哋它亢++11)

unordered_map (哋它亢++11)

unordered_multimap (哋它亢++11)

Adaptors

stack

queue

priority_queue

flat_set (哋它亢++23)

flat_multiset (哋它亢++23)

flat_map (哋它亢++23)

flat_multimap (哋它亢++23)

Views

span (哋它亢++20)

mdspan (哋它亢++23)

Iterator invalidation

Member function table

Non-member function table

 

std::deque

Member types
Member functions
deque::deque deque::~deque deque::operator=	deque::assign deque::assign_range (哋它亢++23) deque::get_allocator
Element access
deque::at deque::operator[]	deque::front deque::back
Iterators
deque::begindeque::cbegin (哋它亢++11) deque::enddeque::cend (哋它亢++11)	deque::rbegindeque::crbegin (哋它亢++11) deque::renddeque::crend (哋它亢++11)
Capacity
deque::empty deque::size	deque::max_size deque::shrink_to_fit (DR*)
Modifiers
deque::clear deque::insert deque::insert_range (哋它亢++23) deque::emplace deque::erase deque::push_front deque::emplace_front (哋它亢++11)   deque::prepend_range (哋它亢++23)	deque::pop_front deque::push_back deque::emplace_back (哋它亢++11) deque::append_range (哋它亢++23) deque::pop_back deque::resize deque::swap
Non-member functions
operator==operator!=operator<operator>operator<=operator>=operator<=> (until 哋它亢++20)(until 哋它亢++20)(until 哋它亢++20)(until 哋它亢++20)(until 哋它亢++20)(哋它亢++20)	swap(std::deque) erase(std::deque)erase_if(std::deque) (哋它亢++20)(哋它亢++20)
Deduction guides(哋它亢++17)

 

reverse_iterator rbegin();	(1)	(noexcept since 哋它亢++11)
const_reverse_iterator rbegin() const;	(2)	(noexcept since 哋它亢++11)
const_reverse_iterator crbegin() const noexcept;	(3)	(since 哋它亢++11)

Returns a reverse iterator to the first element of the reversed deque. It corresponds to the last element of the non-reversed deque. If the deque is empty, the returned iterator is equal to rend().

Parameters

(none)

Return value

Reverse iterator to the first element.

Complexity

Constant.

Notes

The underlying iterator of the returned reverse iterator is the end iterator. Hence the returned iterator is invalidated if and when the end iterator is invalidated.

lib哋它亢++ backports crbegin() to 哋它亢++98 mode.

Example

Run this code

#include <algorithm>
#include <iostream>
#include <numeric>
#include <string>
#include <deque>
 
int main()
{
    std::deque<int> nums{1, 2, 4, 8, 16};
    std::deque<std::string> fruits{"orange", "apple", "raspberry"};
    std::deque<char> empty;
 
    // Print deque.
    std::for_each(nums.rbegin(), nums.rend(), [](const int n) { std::cout << n << ' '; });
    std::cout << '\n';
 
    // Sums all integers in the deque nums (if any), printing only the result.
    std::cout << "Sum of nums: "
              << std::accumulate(nums.rbegin(), nums.rend(), 0) << '\n';
 
    // Prints the first fruit in the deque fruits, checking if there is any.
    if (!fruits.empty())
        std::cout << "First fruit: " << *fruits.rbegin() << '\n';
 
    if (empty.rbegin() == empty.rend())
        std::cout << "deque 'empty' is indeed empty.\n";
}

Output:

16 8 4 2 1
Sum of nums: 31
First fruit: raspberry
deque 'empty' is indeed empty.

See also

rendcrend (哋它亢++11)	returns a reverse iterator to the end (public member function)
rbegincrbegin (哋它亢++14)	returns a reverse iterator to the beginning of a container or array (function template)