std::flat_multimap::rend,(3)

okay so this is the std::flat_multimap::rend,(3) page from the C++ Standard Libary manual — welcome to the group chat, bestie 💖. It's the reverse-end iterator page, and yes, the comma in the name is real, we are keeping it.

💅 NAME

std::flat_multimap::rend, — that's literally the name, comma and all, no cap. The NAME line says std::flat_multimap::rend, - std::flat_multimap::rend, — yes it repeats itself, we love a self-obsessed icon 💅. This is the C++ Standard Libary manual's (3) page for the reverse-end iterator situation on std::flat_multimap.

✨ Synopsis ✨

Three overloads, all since C++23, bestie:

reverse_iterator rend() noexcept;              (1) (since C++23)
const_reverse_iterator rend() const noexcept;  (2) (since C++23)
const_reverse_iterator crend() const noexcept; (3) (since C++23)

Returns a reverse iterator to the element following the last element of the reversed flat_multimap. It corresponds to the element preceding the first element of the non-reversed flat_multimap.

This element acts as a placeholder, and attempting to access it results in undefined behavior — so do NOT dereference it, bestie, that's a big yikes 😭.

The original page also has a diagram named range-rbegin-rend.svg right here — imagine the cutest little reverse-iterator visual, because I can't draw it in terminal 💀.

🎀 Parameters 🎀

(none), bestie. Zero args, zero stress, just vibes 🫶.

🔥 Return value 🔥

Reverse iterator to the element following the last element. That's the whole tea, slay ✨.

🌸 Complexity 🌸

Constant. literally constant, periodt — no scaling drama.

🦋 Example 🦋

okay here's the example, copied exactly because we do not mess with code 💅:

       // Run this code

        #include <chrono>
        #include <iomanip>
        #include <iostream>
        #include <string_view>
        #include <flat_map>

        using namespace std::chrono;

        int main()
        {
            const std::flat_multimap<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 : 20
        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 : 24
        2020-04-01 : 42

👑 See also 👑

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

xoxo, from http://cppreference.com 💖 version/date 2024.06.10, all about std::flat_multimap::rend,(3) — byeee bestie 🦋