std::map<Key,T,Compare,Allocator>::rend, std::map<Key,T,Compare,Allocator>::crend

 

C++

Compiler support

Freestanding and hosted

Language

Standard library

Standard library headers

Named requirements

Feature test macros (C++20)

Language support library

Concepts library (C++20)

Metaprogramming library (C++11)

Diagnostics library

General utilities library

Strings library

Containers library

Iterators library

Ranges library (C++20)

Algorithms library

Numerics library

Localizations library

Input/output library

Filesystem library (C++17)

Regular expressions library (C++11)

Concurrency support library (C++11)

Execution support library (C++26)

Technical specifications

Symbols index

External libraries

 

Containers library

Sequence

array (C++11)

vector

vector<bool>

inplace_vector (C++26)

deque

forward_list (C++11)

list

Associative

set

multiset

map

multimap

Unordered associative

unordered_set (C++11)

unordered_multiset (C++11)

unordered_map (C++11)

unordered_multimap (C++11)

Adaptors

stack

queue

priority_queue

flat_set (C++23)

flat_multiset (C++23)

flat_map (C++23)

flat_multimap (C++23)

Views

span (C++20)

mdspan (C++23)

Tables

Iterator invalidation

Member function table

Non-member function table

 

std::map

Member functions

map::map map::~map               map::operator= map::get_allocator

Element access map::at map::operator[] Iterators map::beginmap::cbegin (C++11) map::endmap::cend (C++11) map::rbeginmap::crbegin (C++11)      map::rendmap::crend (C++11) Capacity map::size map::max_size map::empty Observers map::key_comp map::value_comp Modifiers map::clear map::insert map::erase map::swap map::extract (C++17) map::merge (C++17) map::insert_range (C++23) map::insert_or_assign (C++17) map::emplace (C++11) map::emplace_hint (C++11) map::try_emplace (C++17) Lookup map::count map::find map::contains (C++20) map::equal_range map::lower_bound map::upper_bound

Non-member functions

operator==operator<=> (C++20) std::swap(std::map) erase_if(std::map) (C++20)   operator!=operator<operator>operator<=operator>= (until C++20)(until C++20)(until C++20)(until C++20)(until C++20)

Deduction guides (C++17)

 

reverse_iterator rend();	(1)	(noexcept since C++11)
const_reverse_iterator rend() const;	(2)	(noexcept since C++11)
const_reverse_iterator crend() const noexcept;	(3)	(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.

Parameters

(none)

Return value

Reverse iterator to the element following the last element.

Complexity

Constant.

Notes

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

Example

Run this code

#include <chrono>
#include <iomanip>
#include <iostream>
#include <string_view>
#include <map>
 
using namespace std::chrono;
 
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 (date order is reversed):\n";
    for (auto it = messages.crbegin(); it != messages.crend(); ++it)
        std::cout << it->first << " : " << it->second << '\n';
}

Possible output:

Messages received (date order is reversed):
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

rbegincrbegin (C++11)	returns a reverse iterator to the beginning (public member function)
rendcrend (C++14)	returns a reverse end iterator for a container or array (function template)