std::basic_string::rend,(3)

🎀 std::basic_string::rend,(3) — C++ Standard Library vibes 🎀

okay bestie, welcome to the C++ Standard Library corner of the group chat 💅 this page is all about std::basic_string::rend, — yes the title literally has a comma in it, we don't make the rules, we just slay ✨

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✨ NAME ✨

std::basic_string::rend, — literally std::basic_string::rend, 🫶 that's the name, comma and all, no cap.

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🦋 Synopsis 🦋

reverse_iterator rend();                       (1) (noexcept since C++11)
                                                    (constexpr since C++20)
const_reverse_iterator rend() const;           (2) (noexcept since C++11)
                                                    (constexpr since C++20)
const_reverse_iterator crend() const noexcept; (3) (since C++11)
                                                    (constexpr since C++20)

so we've got three overloads doing their lil reverse-iterator thing 💖 overload (1) is the non-const rend(), overload (2) is the const rend(), and overload (3) is crend(), which is noexcept and showed up in C++11 👑

quick vibe check on the annotations, because they matter:

• (1) is noexcept since C++11 and constexpr since C++20
• (2) is noexcept since C++11 and constexpr since C++20
• (3) is noexcept, since C++11, and constexpr since C++20

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🌸 Description 🌸

Returns a reverse iterator to the character following the last character of the reversed string 🔁 It corresponds to the character preceding the first character of the non-reversed string.

that character is literally just a placeholder, bestie — attempting to access it results in undefined behavior 😭 so don't do it, fr fr.

there's also a diagram referenced in the original as range-rbegin-rend.svg 🦋 imagine a cute lil range picture right here.

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🌺 Parameters 🌺

none 😌 zero. nada. no arguments. it's giving low-maintenance icon.

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💖 Return value 💖

Reverse iterator to the character following the last character ✨ that's it, that's the whole return value.

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⭐ Complexity ⭐

Constant 🔥 O(1) energy, no cap.

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🧚 Notes 🧚

libc++ backports crend() to C++98 mode 👀 that's the note. that's the whole note. iconic behavior honestly.

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🔥 Example 🔥

// Run this code

#include <algorithm>
#include <iostream>
#include <iterator>
#include <string>

int main()
{
    std::string p("[A man, a plan, a canal: Panama]");
    std::string q;

    std::copy(p.crbegin(), p.crend(), std::back_inserter(q));
    std::cout << "q = " << q << '\n';

    std::copy(q.crbegin(), q.crend(), p.rbegin());
    std::cout << "p = " << p << '\n';
}

🌈 Output 🌈

q = ]amanaP :lanac a ,nalp a ,nam A[
p = ]amanaP :lanac a ,nalp a ,nam A[

look at that palindrome getting reversed twice and ending up exactly where it started 😌 ate and left no crumbs 💅

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👑 See also 👑

• rbegin — returns a reverse iterator to the beginning
• crbegin — (public member function) (C++11)
• rend — returns a reverse iterator to the end
• crend — (public member function of std::basic_string_view<CharT,Traits>)

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shoutout to http://cppreference.com for the source, and the 2024.06.10 date on the original page — this was std::basic_string::rend,(3), mwah 🫶💜