NAME¶

std::map::rend,std::map::crend - std::map::rend,std::map::crend

Synopsis¶

reverse_iterator rend(); (until C++11)
reverse_iterator rend() noexcept; (since C++11)
const_reverse_iterator rend() const; (until C++11)
const_reverse_iterator rend() const noexcept; (since C++11)
const_reverse_iterator crend() const noexcept; (since C++11)

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

range-rbegin-rend.svg

Parameters¶

(none)

Return value¶

Reverse iterator to the element following the last element.

Complexity¶

Constant.

Example¶

// Run this code

#include <iostream>
#include <iomanip>
#include <chrono>
#include <map>
#include <string_view>
using namespace std::chrono;

// until C++20 chrono operator<< ready
std::ostream& operator<<(std::ostream& os, const year_month_day& ymd) {
return os << std::setfill('0') << static_cast<int>(ymd.year()) << '/'
<< std::setw(2) << static_cast<unsigned>(ymd.month()) << '/'
<< std::setw(2) << static_cast<unsigned>(ymd.day());
}

int main()
{
const std::map<year_month_day, int> messages {
{ February/17/2023 , 10 },
{ February/17/2023 , 20 },
{ February/16/2022 , 30 },
{ October/22/2022 , 40 },
{ June/14/2022 , 50 },
{ November/23/2021 , 60 },
{ December/10/2022 , 55 },
{ December/12/2021 , 45 },
{ April/1/2020 , 42 },
{ April/1/2020 , 24 },
};
std::cout << "Messages received, reverse date order:\n";
for (auto it = messages.crbegin(); it != messages.crend(); ++it) {
std::cout << it->first << " : " << it->second << '\n';
}
}

Possible output:¶

Messages received, reverse date order:
2023/02/17 : 10
2022/12/10 : 55
2022/10/22 : 40
2022/06/14 : 50
2022/02/16 : 30
2021/12/12 : 45
2021/11/23 : 60
2020/04/01 : 42

See also¶

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