std::list::...list::crend(3)

okay bestie, this is the std::list::...list::crend(3) page from the C++ Standard Libary manual — yes, that spelling is the manual’s, and we’re keeping it 💅.

✨ NAME ✨

std::list::rend,std::list::crend - std::list::rend,std::list::crend

these are the reverse-end besties for std::list — the iconique duo rend + crend 💖.

🌸 Synopsis 🌸

here’s the signature lineup, no cap:

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)

• (1) — reverse_iterator rend();, and it’s noexcept since C++11 ✨
• (2) — const_reverse_iterator rend() const;, also noexcept since C++11 🎀
• (3) — const_reverse_iterator crend() const noexcept;, since C++11 🦋

so what’s the vibe? rend() and crend() return a reverse iterator to the element following the last element of the reversed list. It corresponds to the element preceding the first element of the non-reversed list. This element acts as a placeholder — attempting to access it results in undefined behavior 😭💀, so do not play with it.

the original also has a diagram file called range-rbegin-rend.svg if you want the visual 🦋.

🎀 Parameters 🎀

(none) — literally no parameters, bestie. nothing to pass, nothing to stress about 🫶.

💖 Return value 💖

Reverse iterator to the element following the last element. that’s the whole sentence, periodt 💅.

⭐ Complexity ⭐

Constant. lowkey effortless, highkey constant ✨.

🧚 Notes 🧚

libc++ backports crend() to C++98 mode. that’s the note, iykyk 🧚.

🍓 Example 🍓

// Run this code

        #include <algorithm>
        #include <iostream>
        #include <numeric>
        #include <string>
        #include <list>

        int main()
        {
            std::list<int> nums{1, 2, 4, 8, 16};
            std::list<std::string> fruits{"orange", "apple", "raspberry"};
            std::list<char> empty;

            // Print list.
            std::for_each(nums.rbegin(), nums.rend(), [](const int n) {
       std::cout << n << ' '; });
            std::cout << '\n';

            // Sums all integers in the list 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 list fruits, checking if there is
       any.
            if (!fruits.empty())
                std::cout << "First fruit: " << *fruits.rbegin() << '\n';

            if (empty.rbegin() == empty.rend())
                std::cout << "list 'empty' is indeed empty.\n";
        }

🍓 Output: 🍓

16 8 4 2 1
Sum of nums: 31
First fruit: raspberry
list 'empty' is indeed empty.

🌈 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)

💜 and that’s the std::list::...list::crend(3) page, bestie — source/version: http://cppreference.com, dated 2024.06.10. mwah 💅✨