std::deque:...eque::crend(3)

💖 NAME 💖

Hey bestie 💖 welcome to the std::deque::rend / std::deque::crend page, aka std::deque:...eque::crend(3), from the C++ Standard Libary (yes, that's the spelling up top, she's quirky 💀).

std::deque::rend,std::deque::crend — std::deque::rend,std::deque::crend (the name really said it twice, and honestly? iconic 💅).

---

✨ Synopsis ✨

• 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

Okay so what does it do? It returns a reverse iterator to the element following the last element of the reversed deque. In non-reversed brain terms: it corresponds to the element preceding the first element of the non-reversed deque. This element acts as a placeholder, and attempting to access it results in undefined behavior 😭🚨 — so do not touch the placeholder, bestie, fr fr.

Diagram vibe check: range-rbegin-rend.svg 🎀✨

---

🌸 Parameters 🌸

(none) 🫶 — she takes no arguments, low-maintenance queen.

---

💫 Return value 💫

Reverse iterator to the element following the last element. Periodt. 💅

---

🦋 Complexity 🦋

Constant. O(1), no cap ✨.

---

🎀 Notes 🎀

libc++ backports crend() to C++98 mode. Cute of her, honestly 🫶.

---

🍓 Example 🍓

The example starts with // Run this code, so bestie, run it 🏃‍♀️💨:

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

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

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

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

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

Output:

16 8 4 2 1
Sum of nums: 31
First fruit: raspberry
deque '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)

---

Source: http://cppreference.com · version/date: 2024.06.10 · page: std::deque:...eque::crend(3) — bye bestie, go reverse-iterate slayfully 💅✨💖