std::rotl(3)

🌸 NAME 🌸

okay bestie, welcome to std::rotl from the C++ Standard Libary manual — yes, that’s the manual name, typo and all 😭💅. this page is std::rotl(3).

• std::rotl — std::rotl

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✨ Synopsis ✨

Defined in header <bit>.

template< class T >                                     (since C++20)
[[nodiscard]] constexpr T rotl( T x, int s ) noexcept;

okay so what does it do? it computes the result of bitwise left-rotating the value of x by s positions. this operation is also known as a left circular shift 🌀✨.

formally, let N be std::numeric_limits<T>::digits, and let r be s % N.

• If r is 0, returns x;
• if r is positive, returns (x << r) | (x >> (N - r));
• if r is negative, returns std::rotr(x, -r).

this overload participates in overload resolution only if T is an unsigned integer type (that is, unsigned char, unsigned short, unsigned int, unsigned long, unsigned long long, or an extended unsigned integer type). no sneaky signed types, bestie 🚫💀.

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🎀 Parameters 🎀

• x — value of unsigned integer type
• s — number of positions to shift

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🦋 Return value 🦋

the result of bitwise left-rotating x by s positions. periodt 💅

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💜 Notes 💜

feature-test macro vibe check:

• Feature-test macro: __cpp_lib_bitops — value: 201907L, std: (C++20), feature: Bit operations

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🍓 Example 🍓

// Run this code

#include <bit>
#include <bitset>
#include <cstdint>
#include <iostream>

int main()
{
    const std::uint8_t i = 0b00011101;
    std::cout << "i          = " << std::bitset<8>(i) << '\n';
    std::cout << "rotl(i,0)  = " << std::bitset<8>(std::rotl(i, 0)) << '\n';
    std::cout << "rotl(i,1)  = " << std::bitset<8>(std::rotl(i, 1)) << '\n';
    std::cout << "rotl(i,4)  = " << std::bitset<8>(std::rotl(i, 4)) << '\n';
    std::cout << "rotl(i,9)  = " << std::bitset<8>(std::rotl(i, 9)) << '\n';
    std::cout << "rotl(i,-1) = " << std::bitset<8>(std::rotl(i, -1)) << '\n';
}

Output:

i          = 00011101
rotl(i,0)  = 00011101
rotl(i,1)  = 00111010
rotl(i,4)  = 11010001
rotl(i,9)  = 00111010
rotl(i,-1) = 10001110

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👀 See also 👀

• rotr — computes the result of bitwise right-rotation (C++20) (function template)
• operator<<=
• operator>>= — performs binary shift left and shift right
• operator<< — (public member function of std::bitset<N>)
• operator>>

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byeee bestie 🫶💖 this page is from <http://cppreference.com>, dated 2024.06.10 — std::rotl(3), muah 💋✨