Standard library header <bit>

 

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Standard library headers

Language support <cfloat> <climits> <compare> (C++20) <coroutine> (C++20) <csetjmp> <csignal> <cstdarg> <cstddef> <cstdint> (C++11) <cstdlib> <exception> <initializer_list> (C++11)    <limits> <new> <source_location> (C++20) <stdfloat> (C++23) <typeinfo> <version> (C++20) Concepts <concepts> (C++20) Diagnostics <cassert> <cerrno> <debugging> (C++26) <stacktrace> (C++23) <stdexcept> <system_error> (C++11) Memory management <memory> <memory_resource> (C++17) <scoped_allocator> (C++11) Metaprogramming <type_traits> (C++11) <ratio> (C++11)

General utilities <any> (C++17) <bitset> <bit> (C++20) <charconv> (C++17) <expected> (C++23) <format> (C++20) <functional> <optional> (C++17) <tuple> (C++11) <typeindex> (C++11) <utility> <variant> (C++17) Containers <array> (C++11) <deque> <flat_map> (C++23) <flat_set> (C++23) <forward_list> (C++11) <inplace_vector> (C++26)    <list> <map> <mdspan> (C++23) <queue> <set> <span> (C++20) <stack> <unordered_map> (C++11) <unordered_set> (C++11) <vector> Iterators <iterator> Ranges <generator> (C++23) <ranges> (C++20)

Algorithms <algorithm> <numeric> Strings <cctype> <cstring> <cuchar> (C++11) <cwchar> <cwctype> <string_view> (C++17) <string> Text processing <clocale> <codecvt> (C++11/17/26*) <locale> <regex> (C++11) <text_encoding> (C++26)    Numerics <cfenv> (C++11) <cmath> <complex> <linalg> (C++26) <numbers> (C++20) <random> (C++11) <valarray> Time <chrono> (C++11) <ctime> C compatibility <ccomplex> (C++11/17/20*) <ciso646> (until C++20) <cstdalign> (C++11/17/20*) <cstdbool> (C++11/17/20*) <ctgmath> (C++11/17/20*)

Input/output <cinttypes> (C++11) <cstdio> <filesystem> (C++17) <fstream> <iomanip> <iosfwd> <iostream> <ios> <istream> <ostream> <print> (C++23) <spanstream> (C++23) <sstream> <streambuf> <strstream> (C++98/26*) <syncstream> (C++20) Concurrency support <atomic> (C++11) <barrier> (C++20) <condition_variable> (C++11) <future> (C++11) <hazard_pointer> (C++26) <latch> (C++20) <mutex> (C++11) <rcu> (C++26) <semaphore> (C++20) <shared_mutex> (C++14) <stdatomic.h> (C++23) <stop_token> (C++20) <thread> (C++11) Execution support <execution> (C++17)

 

This header is part of the numeric library.

Functions

bit_cast (C++20)	reinterpret the object representation of one type as that of another (function template)
has_single_bit (C++20)	checks if a number is an integral power of 2 (function template)
bit_ceil (C++20)	finds the smallest integral power of two not less than the given value (function template)
bit_floor (C++20)	finds the largest integral power of two not greater than the given value (function template)
bit_width (C++20)	finds the smallest number of bits needed to represent the given value (function template)
rotl (C++20)	computes the result of bitwise left-rotation (function template)
rotr (C++20)	computes the result of bitwise right-rotation (function template)
countl_zero (C++20)	counts the number of consecutive ​0​ bits, starting from the most significant bit (function template)
countl_one (C++20)	counts the number of consecutive 1 bits, starting from the most significant bit (function template)
countr_zero (C++20)	counts the number of consecutive ​0​ bits, starting from the least significant bit (function template)
countr_one (C++20)	counts the number of consecutive 1 bits, starting from the least significant bit (function template)
popcount (C++20)	counts the number of 1 bits in an unsigned integer (function template)

Types

endian (C++20)

indicates the endianness of scalar types (enum)

Synopsis

namespace std {
    // bit_cast
    template<typename To, typename From>
    constexpr To bit_cast(const From& from) noexcept;
 
    // integral powers of 2
    template <class T>
    constexpr bool has_single_bit(T x) noexcept;
    template <class T>
    constexpr T ceil2(T x);
    template <class T>
    constexpr T floor2(T x) noexcept;
    template <class T>
    constexpr T log2p1(T x) noexcept;
 
    // rotating
    template<class T>
    [[nodiscard]] constexpr T rotl(T x, int s) noexcept;
    template<class T>
    [[nodiscard]] constexpr T rotr(T x, int s) noexcept;
 
    // counting
    template<class T>
    constexpr int countl_zero(T x) noexcept;
    template<class T>
    constexpr int countl_one(T x) noexcept;
    template<class T>
    constexpr int countr_zero(T x) noexcept;
    template<class T>
    constexpr int countr_one(T x) noexcept;
    template<class T>
    constexpr int popcount(T x) noexcept;
 
    // endian
    enum class endian {
        little = /*implementation-defined*/,
        big    = /*implementation-defined*/,
        native = /*implementation-defined*/
    };
}