std::bitset::test(3)

✨ std::bitset::test ✨

okay bestie, welcome to the std::bitset::test(3) page from the C++ Standard Libary corner of cppreference 💖 this is literally the safe little bit-checker with a bounds check, and it's giving "trust me bestie, I checked" energy 🎀

💖 NAME 💖

std::bitset::test - std::bitset::test (yes bestie, that's the whole name, iconic 💅)

🦋 Synopsis 🦋

bool test( std::size_t pos ) const;  (constexpr since C++23)

okay so this returns the value of the bit at the position pos (counting from 0) ✨

unlike operator[], it performs a bounds check and throws std::out_of_range if pos does not correspond to a valid position in the bitset. like, it's not just vibing, it's actually checking the vibes first 💅

🎀 Parameters 🎀

• pos — position of the bit to return (counting from 0) 🫶

🌸 Return value 🌸

true if the requested bit is set, false otherwise. periodt. ✨

🔥 Exceptions 🔥

std::out_of_range if pos does not correspond to a valid position within the bitset. no cap, it will throw 😭

👑 Example 👑

the page says // Run this code, so literally run it, bestie 👇

#include <bit>
#include <bitset>
#include <cassert>
#include <iostream>
#include <stdexcept>

int main()
{
    std::bitset<10> b1("1111010000");

    std::size_t idx = 0;
    while (idx < b1.size() && !b1.test(idx))
        ++idx;

    assert(static_cast<int>(idx) == std::countr_zero(b1.to_ulong()));

    if (idx < b1.size())
        std::cout << "The first set bit is at index " << idx << '\n';
    else
        std::cout << "no set bits\n";

    try
    {
        std::bitset<0B10'1001'1010> bad;
        if (bad.test(bad.size()))
            std::cout << "Expect unexpected!\n";
    }
    catch (std::out_of_range const& ex)
    {
        std::cout << "Exception: " << ex.what() << '\n';
    }
}

possible output, slay:

The first set bit is at index 4
Exception: bitset::test: __position (which is 666) >= _Nb (which is 666)

🌈 See also 🌈

• operator[] — accesses specific bit (public member function) 💅
• popcount — counts the number of 1 bits in an unsigned integer (C++20) (function template) ✨
• has_single_bit — checks if a number is an integral power of 2 (C++20) (function template) 👑

and that's the whole page, bestie 🫶 source/version/date realness: this came from http://cppreference.com, dated 2024.06.10, and the page is literally std::bitset::test(3) 💖 bye bestie, go test those bits responsibly 💅✨