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/C++std::vector<T,Allocator>::rbegin, std::vector<T,Allocator>::crbegin
| (1) | ||
reverse_iterator rbegin(); | (until C++11) | |
reverse_iterator rbegin() noexcept; | (since C++11) (until C++20) | |
constexpr reverse_iterator rbegin() noexcept; | (since C++20) | |
| (2) | ||
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) | |
| (3) | ||
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().
Parameters
(none).
Return value
Reverse iterator to the first element.
Complexity
Constant.
Example
#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
|
(C++11) | returns a reverse iterator to the end (public member function) |
|
(C++14) | returns a reverse iterator to the beginning of a container or array (function template) |
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