Standard library header <bitset>

 

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Language support <cfloat> <climits> <compare> (C++20) <contracts> (C++26) <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) <stdbit.h> (C++26) <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) <hive> (C++26) <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) <simd> (C++26) <stdckdint.h> (C++26) <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)

 

See More

This header is part of the general utility library.

Includes
<string>	std::basic_string class template
<iosfwd>	Forward declarations of all classes in the input/output library
Classes
bitset	implements constant length bit array (class template)
std::hash<std::bitset> (C++11)	hash support for std::bitset (class template specialization)
Forward declarations
Defined in header <functional>
hash (C++11)	hash function object (class template)
Functions
operator&operator|operator^	performs binary logic operations on bitsets (function template)
operator<<operator>>	performs stream input and output of bitsets (function template)

Synopsis

#include <string>
#include <iosfwd>   // for istream, ostream

namespace std {
  template<size_t N> class bitset;

  // bitset operators
  template<size_t N>
    constexpr bitset<N> operator&(const bitset<N>&, const bitset<N>&) noexcept;
  template<size_t N>
    constexpr bitset<N> operator|(const bitset<N>&, const bitset<N>&) noexcept;
  template<size_t N>
    constexpr bitset<N> operator^(const bitset<N>&, const bitset<N>&) noexcept;
  template<class CharT, class Traits, size_t N>
    basic_istream<CharT, Traits>&
      operator>>(basic_istream<CharT, Traits>& is, bitset<N>& x);
  template<class CharT, class Traits, size_t N>
    basic_ostream<CharT, Traits>&
      operator<<(basic_ostream<CharT, Traits>& os, const bitset<N>& x);
}

Class template std::bitset

namespace std {
  template<size_t N> class bitset {
  public:
    // bit reference
    class reference {
    public:
      constexpr reference(const reference&) = default;
      constexpr ~reference();
      constexpr reference& operator=(bool x) noexcept;           // for b[i] = x;
      constexpr reference& operator=(const reference&) noexcept; // for b[i] = b[j];
      constexpr bool operator~() const noexcept;                 // flips the bit
      constexpr operator bool() const noexcept;                  // for x = b[i];
      constexpr reference& flip() noexcept;                      // for b[i].flip();
    };

    // constructors
    constexpr bitset() noexcept;
    constexpr bitset(unsigned long long val) noexcept;
    template<class CharT, class Traits, class Allocator>
      constexpr explicit bitset(
        const basic_string<CharT, Traits, Allocator>& str,
        typename basic_string<CharT, Traits, Allocator>::size_type pos = 0,
        typename basic_string<CharT, Traits, Allocator>::size_type n
          = basic_string<CharT, Traits, Allocator>::npos,
        CharT zero = CharT('0'),
        CharT one = CharT('1'));
    template<class CharT, class Traits>
      constexpr explicit bitset(
        basic_string_view<CharT, Traits> str,
        typename basic_string_view<CharT, Traits>::size_type pos = 0,
        typename basic_string_view<CharT, Traits>::size_type n
          = basic_string_view<CharT, Traits>::npos,
        CharT zero = CharT('0'),
        CharT one = CharT('1'));
    template<class CharT>
      constexpr explicit bitset(
        const CharT* str,
        typename basic_string_view<CharT>::size_type n = basic_string_view<CharT>::npos,
        CharT zero = CharT('0'),
        CharT one = CharT('1'));

    // bitset operations
    constexpr bitset& operator&=(const bitset& rhs) noexcept;
    constexpr bitset& operator|=(const bitset& rhs) noexcept;
    constexpr bitset& operator^=(const bitset& rhs) noexcept;
    constexpr bitset& operator<<=(size_t pos) noexcept;
    constexpr bitset& operator>>=(size_t pos) noexcept;
    constexpr bitset  operator<<(size_t pos) const noexcept;
    constexpr bitset  operator>>(size_t pos) const noexcept;
    constexpr bitset& set() noexcept;
    constexpr bitset& set(size_t pos, bool val = true);
    constexpr bitset& reset() noexcept;
    constexpr bitset& reset(size_t pos);
    constexpr bitset  operator~() const noexcept;
    constexpr bitset& flip() noexcept;
    constexpr bitset& flip(size_t pos);

    // element access
    constexpr bool operator[](size_t pos) const;
    constexpr reference operator[](size_t pos);

    constexpr unsigned long to_ulong() const;
    constexpr unsigned long long to_ullong() const;
    template<class CharT = char,
             class Traits = char_traits<CharT>,
             class Allocator = allocator<CharT>>
      constexpr basic_string<CharT, Traits, Allocator>
        to_string(CharT zero = CharT('0'), CharT one = CharT('1')) const;

    // observers
    constexpr size_t count() const noexcept;
    constexpr size_t size() const noexcept;
    constexpr bool operator==(const bitset& rhs) const noexcept;
    constexpr bool test(size_t pos) const;
    constexpr bool all() const noexcept;
    constexpr bool any() const noexcept;
    constexpr bool none() const noexcept;
  };

  // hash support
  template<class T> struct hash;
  template<size_t N> struct hash<bitset<N>>;
}

Defect reports

The following behavior-changing defect reports were applied retroactively to previously published C++ standards.

DR	Applied to	Behavior as published	Correct behavior
LWG 4140	C++98	the synopsis contains a declaration of the default constructor of std::bitset<N>::reference	removed the declaration