std::bitset::reference(3)

💅 std::bitset::reference — C++ Standard Library, section 3 (bestie edition)

okay so you're poking around in the C++ Standard Library, huh? This page is std::bitset::reference(3), and honestly? it's giving tiny-but-mighty. let's get into it 🎀

---

✨ NAME ✨

std::bitset::reference — literally std::bitset::reference 💖

---

🌸 SYNOPSIS 🌸

class reference;

so the std::bitset class includes std::bitset::reference as a publicly-accessible nested class. yes, nested. like a little bestie living inside the bitset 💅

what is it for? okay so listen — this class is used as a proxy object to let you interact with individual bits of a bitset. and why do we even need that? because standard C++ types (like references and pointers) are not built with enough precision to specify individual bits. like... they just can't point that fine. it's giving "trying to point at a single crumb in a whole cake" 😭

the primary use of std::bitset::reference is to provide an lvalue that can be returned from operator[]. iconic behavior honestly 👑

⚠️ heads up bestie: any reads or writes to a bitset that happen via a std::bitset::reference potentially read or write to the entire underlying bitset. so like... it's a proxy, not a laser. noted. 🫶

---

🦋 Member functions 🦋

• constructor — constructs the reference. Accessible only to std::bitset itself (private member function) 🙈
• destructor — destroys the reference (public member function)
• operator= — assigns a bool to the referenced bit (public member function)
• operator bool — returns the referenced bit (public member function)
• operator~ — returns inverted referenced bit (public member function)
• flip — flips the referenced bit (public member function)

---

🌈 std::bitset<N>::reference::~reference

~reference();  (constexpr since C++23)

Destroys the reference. that's it. that's the whole vibe. bye bestie 👋✨

---

🌈 std::bitset<N>::reference::operator=

reference& operator=( bool x );                    (until C++11)
                                                   (since C++11)
reference& operator=( bool x ) noexcept;           (constexpr since C++23)
reference& operator=( const reference& x );        (1) (until C++11)
reference& operator=( const reference& x ) noexcept; (2) (since C++11)
                                                   (constexpr since C++23)

Assigns a value to the referenced bit. slay, we love a good assignment 💅

🌟 Parameters

• x — value to assign

🌟 Return value

*this

---

🌈 std::bitset<N>::reference::operator bool

operator bool() const;           (until C++11)
operator bool() const noexcept;  (since C++11)
                                 (constexpr since C++23)

Returns the value of the referenced bit. the moment of truth honestly 💀

🌟 Parameters

(none)

🌟 Return value

The referenced bit.

---

🌈 std::bitset<N>::reference::operator~

bool operator~() const;           (until C++11)
bool operator~() const noexcept;  (since C++11)
                                  (constexpr since C++23)

Returns the inverse of the referenced bit. flipping it with style 🦋

🌟 Parameters

(none)

🌟 Return value

The inverse of the referenced bit.

---

🌈 std::bitset<N>::reference::flip

reference& flip();           (until C++11)
reference& flip() noexcept;  (since C++11)
                             (constexpr since C++23)

Inverts the referenced bit. not a read, not a copy — an actual flip. periodt. 🔥

🌟 Parameters

(none)

🌟 Return value

*this

---

🧚 Example 🧚

// Run this code

#include <bitset>
#include <iostream>

int main()
{
    std::bitset<4> bs{0b1110};

    std::bitset<4>::reference ref = bs[2];

    auto info = [&](int id)
    {
        std::cout << id << ") bs: " << bs << "; ref bit: " << ref << '\n';
    };

    info(1);
    ref = false;
    info(2);
    ref = true;
    info(3);
    ref.flip();
    info(4);
    ref = bs[1]; // operator=( const reference& x )
    info(5);

    std::cout << "6) ~ref bit: " << ~ref << '\n';
}

⭐ Output:

1) bs: 1110; ref bit: 1
2) bs: 1010; ref bit: 0
3) bs: 1110; ref bit: 1
4) bs: 1010; ref bit: 0
5) bs: 1110; ref bit: 1
6) ~ref bit: 0

look at that little proxy doing its thing, we love to see it 🥹💜

---

👑 See also 👑

• operator[] — accesses specific bit (public member function)

---

that's the whole page, bestie!! no cap, you're now a std::bitset::reference expert 🎀✨

💌 this gem came from http://cppreference.com, version 2024.06.10, and the page itself is std::bitset::reference(3). go forth and flip bits responsibly 🐛🌸