std::set::r...et::crbegin(3)

💅 NAME 💅

okay bestie, this is the std::set::r...et::crbegin(3) page from the C++ Standard Libary manual (yes, “Libary” is exactly how the header spells it 💀), and it’s all about std::set::rbegin,std::set::crbegin. The name line is literally std::set::rbegin,std::set::crbegin - std::set::rbegin,std::set::crbegin — iconic, no notes.

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🎀 Synopsis 🎀

okay so here are the three overloads, bestie — exactly as written, version tags and all:

reverse_iterator rbegin();                       (1) (noexcept since C++11)
const_reverse_iterator rbegin() const;           (2) (noexcept since C++11)
const_reverse_iterator crbegin() const noexcept; (3) (since C++11)

Returns a reverse iterator to the first element of the reversed set. It corresponds to the last element of the non-reversed set. If the set is empty, the returned iterator is equal to rend().

there’s also a diagram in the original named range-rbegin-rend.svg — visual queen behavior ✨

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🧸 Parameters 🧸

(none) — zero, zilch, no args, bestie 🫶

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🌈 Return value 🌈

Reverse iterator to the first element.

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🔥 Complexity 🔥

Constant. literally constant, no cap.

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💜 Notes 💜

Because both iterator and const_iterator are constant iterators (and may in fact be the same type), it is not possible to mutate the elements of the container through an iterator returned by any of these member functions. periodt 💅

The underlying iterator of the returned reverse iterator is the end iterator. Hence the returned iterator is invalidated if and when the end iterator is invalidated. so like, watch out for that invalidation moment 👀

libc++ backports crbegin() to C++98 mode. slay for the old-school girlies.

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🌸 Example 🌸

// Run this code

#include <iostream>
#include <set>

int main()
{
    std::set<unsigned> rep{1, 2, 3, 4, 1, 2, 3, 4};

    for (auto it = rep.crbegin(); it != rep.crend(); ++it)
    {
        for (auto n = *it; n > 0; --n)
            std::cout << "⏼" << ' ';
        std::cout << '\n';
    }
}

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🍓 Output 🍓

⏼ ⏼ ⏼ ⏼
⏼ ⏼ ⏼
⏼ ⏼
⏼

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✨ See also ✨

• rend — returns a reverse iterator to the end
• crend — (public member function) (C++11)
• rbegin — returns a reverse iterator to the beginning of a container or array
• crbegin — (function template) (C++14)

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mwah 💋 — source/version and date: http://cppreference.com, 2024.06.10, page std::set::r...et::crbegin(3).