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std::vector<T,Allocator>::rend, std::vector<T,Allocator>::crend

From cppreference.com
< cpp‎ | container‎ | vector
 
 
 
 
reverse_iterator rend();
(until C++11)
reverse_iterator rend() noexcept;
(since C++11)
(until C++20)
constexpr reverse_iterator rend() noexcept;
(since C++20)
const_reverse_iterator rend() const;
(until C++11)
const_reverse_iterator rend() const noexcept;
(since C++11)
(until C++20)
constexpr const_reverse_iterator rend() const noexcept;
(since C++20)
const_reverse_iterator crend() const noexcept;
(since C++11)
(until C++20)
constexpr const_reverse_iterator crend() const noexcept;
(since C++20)

Returns a reverse iterator to the element following the last element of the reversed vector. It corresponds to the element preceding the first element of the non-reversed vector. This element acts as a placeholder, attempting to access it results in undefined behavior.

range-rbegin-rend.svg

Contents

[edit] Parameters

(none)

[edit] Return value

Reverse iterator to the element following the last element.

[edit] Complexity

Constant.


[edit] 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.

[edit] See also

returns a reverse iterator to the beginning
(public member function) [edit]