NAME¶

std::vector::rbegin,std::vector::crbegin - std::vector::rbegin,std::vector::crbegin

Synopsis¶

reverse_iterator rbegin(); (until C++11)
reverse_iterator rbegin() noexcept; (since C++11)
(until C++20)
constexpr reverse_iterator rbegin() noexcept; (since C++20)
const_reverse_iterator rbegin() const; (until C++11)
const_reverse_iterator rbegin() const noexcept; (since C++11)
(until C++20)
constexpr const_reverse_iterator rbegin() const noexcept; (since C++20)
const_reverse_iterator crbegin() const noexcept; (since C++11)
(until C++20)
constexpr const_reverse_iterator crbegin() const noexcept; (since C++20)

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

range-rbegin-rend.svg

Parameters¶

(none)

Return value¶

Reverse iterator to the first element.

Complexity¶

Constant.

Example¶

// Run this code

#include <algorithm>
#include <iostream>
#include <numeric>
#include <string>
#include <vector>

int main()
{
std::vector<int> nums {1, 2, 4, 8, 16};
std::vector<std::string> fruits {"orange", "apple", "raspberry"};
std::vector<char> empty;

// Print vector.
std::for_each(nums.rbegin(), nums.rend(), [](const int n) { std::cout << n << ' '; });
std::cout << '\n';

// Sums all integers in the vector 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 vector fruits, checking if there is any.
if (!fruits.empty())
std::cout << "First fruit: " << *fruits.rbegin() << '\n';

if (empty.rbegin() == empty.rend())
std::cout << "vector 'empty' is indeed empty.\n";
}

Output:¶

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

See also¶

rend returns a reverse iterator to the end
crend (public member function)
(C++11)
rbegin returns a reverse iterator to the beginning of a container or array
crbegin (function template)
(C++14)