NAME¶

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

Synopsis¶

reverse_iterator rbegin(); (1) (noexcept since C++11)
(constexpr since C++20)
const_reverse_iterator rbegin() const; (2) (noexcept since C++11)
(constexpr since C++20)
const_reverse_iterator crbegin() const noexcept; (3) (since C++11)
(constexpr 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.

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.

libc++ backports crbegin() to C++98 mode.

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)