[bitset.members]

# 22 General utilities library [[utilities]](./#utilities)

## 22.9 Bitsets [[bitset]](bitset#members)

### 22.9.2 Class template bitset [[template.bitset]](template.bitset#bitset.members)

#### 22.9.2.3 Members [bitset.members]

[🔗](#lib:operator&=,bitset)

`constexpr bitset& operator&=(const bitset& rhs) noexcept;
`

[1](#1)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/utilities.tex#L10643)

*Effects*: Clears each bit in*this for which the corresponding bit in rhs is clear, and leaves all other bits unchanged[.](#1.sentence-1)

[2](#2)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/utilities.tex#L10649)

*Returns*: *this[.](#2.sentence-1)

[🔗](#lib:operator%7c=,bitset)

`constexpr bitset& operator|=(const bitset& rhs) noexcept;
`

[3](#3)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/utilities.tex#L10660)

*Effects*: Sets each bit in*this for which the corresponding bit in rhs is set, and leaves all other bits unchanged[.](#3.sentence-1)

[4](#4)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/utilities.tex#L10666)

*Returns*: *this[.](#4.sentence-1)

[🔗](#lib:operator%5e=,bitset)

`constexpr bitset& operator^=(const bitset& rhs) noexcept;
`

[5](#5)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/utilities.tex#L10677)

*Effects*: Toggles each bit in*this for which the corresponding bit in rhs is set, and leaves all other bits unchanged[.](#5.sentence-1)

[6](#6)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/utilities.tex#L10683)

*Returns*: *this[.](#6.sentence-1)

[🔗](#lib:operator%3c%3c=,bitset)

`constexpr bitset& operator<<=(size_t pos) noexcept;
`

[7](#7)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/utilities.tex#L10694)

*Effects*: Replaces each bit at position I in*this with a value determined as follows:

- [(7.1)](#7.1)

If I < pos, the new value is zero;

- [(7.2)](#7.2)

If I >= pos, the new value is the previous
value of the bit at position I - pos[.](#7.sentence-1)

[8](#8)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/utilities.tex#L10707)

*Returns*: *this[.](#8.sentence-1)

[🔗](#lib:operator%3e%3e=,bitset)

`constexpr bitset& operator>>=(size_t pos) noexcept;
`

[9](#9)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/utilities.tex#L10718)

*Effects*: Replaces each bit at position I in*this with a value determined as follows:

- [(9.1)](#9.1)

If pos >= N - I, the new value is zero;

- [(9.2)](#9.2)

If pos < N - I, the new value is the previous value of the bit at position I + pos[.](#9.sentence-1)

[10](#10)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/utilities.tex#L10730)

*Returns*: *this[.](#10.sentence-1)

[🔗](#lib:operator%3c%3c,bitset)

`constexpr bitset operator<<(size_t pos) const noexcept;
`

[11](#11)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/utilities.tex#L10741)

*Returns*: bitset(*this) <<= pos[.](#11.sentence-1)

[🔗](#lib:operator%3e%3e,bitset)

`constexpr bitset operator>>(size_t pos) const noexcept;
`

[12](#12)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/utilities.tex#L10752)

*Returns*: bitset(*this) >>= pos[.](#12.sentence-1)

[🔗](#lib:set_(member),bitset)

`constexpr bitset& set() noexcept;
`

[13](#13)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/utilities.tex#L10765)

*Effects*: Sets all bits in*this[.](#13.sentence-1)

[14](#14)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/utilities.tex#L10770)

*Returns*: *this[.](#14.sentence-1)

[🔗](#lib:set_(member),bitset_)

`constexpr bitset& set(size_t pos, bool val = true);
`

[15](#15)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/utilities.tex#L10783)

*Effects*: Stores a new value in the bit at position pos in*this[.](#15.sentence-1)

If val is true, the stored value is one, otherwise it is zero[.](#15.sentence-2)

[16](#16)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/utilities.tex#L10789)

*Returns*: *this[.](#16.sentence-1)

[17](#17)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/utilities.tex#L10793)

*Throws*: out_of_range if pos does not correspond to a valid bit position[.](#17.sentence-1)

[🔗](#lib:reset,bitset)

`constexpr bitset& reset() noexcept;
`

[18](#18)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/utilities.tex#L10805)

*Effects*: Resets all bits in*this[.](#18.sentence-1)

[19](#19)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/utilities.tex#L10810)

*Returns*: *this[.](#19.sentence-1)

[🔗](#lib:reset,bitset_)

`constexpr bitset& reset(size_t pos);
`

[20](#20)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/utilities.tex#L10821)

*Effects*: Resets the bit at position pos in*this[.](#20.sentence-1)

[21](#21)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/utilities.tex#L10826)

*Returns*: *this[.](#21.sentence-1)

[22](#22)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/utilities.tex#L10830)

*Throws*: out_of_range if pos does not correspond to a valid bit position[.](#22.sentence-1)

[🔗](#lib:operator~,bitset)

`constexpr bitset operator~() const noexcept;
`

[23](#23)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/utilities.tex#L10842)

*Effects*: Constructs an object x of classbitset and initializes it with*this[.](#23.sentence-1)

[24](#24)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/utilities.tex#L10849)

*Returns*: x.flip()[.](#24.sentence-1)

[🔗](#lib:flip,bitset)

`constexpr bitset& flip() noexcept;
`

[25](#25)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/utilities.tex#L10860)

*Effects*: Toggles all bits in*this[.](#25.sentence-1)

[26](#26)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/utilities.tex#L10865)

*Returns*: *this[.](#26.sentence-1)

[🔗](#lib:flip,bitset_)

`constexpr bitset& flip(size_t pos);
`

[27](#27)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/utilities.tex#L10876)

*Effects*: Toggles the bit at position pos in*this[.](#27.sentence-1)

[28](#28)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/utilities.tex#L10881)

*Returns*: *this[.](#28.sentence-1)

[29](#29)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/utilities.tex#L10885)

*Throws*: out_of_range if pos does not correspond to a valid bit position[.](#29.sentence-1)

[🔗](#lib:operator%5b%5d,bitset)

`constexpr bool operator[](size_t pos) const;
`

[30](#30)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/utilities.tex#L10897)

*Hardened preconditions*: pos < size() is true[.](#30.sentence-1)

[31](#31)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/utilities.tex#L10901)

*Returns*: true if the bit at position pos in *this has the value
one, otherwise false[.](#31.sentence-1)

[32](#32)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/utilities.tex#L10906)

*Throws*: Nothing[.](#32.sentence-1)

[🔗](#lib:operator%5b%5d,bitset_)

`constexpr bitset::reference operator[](size_t pos);
`

[33](#33)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/utilities.tex#L10917)

*Hardened preconditions*: pos < size() is true[.](#33.sentence-1)

[34](#34)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/utilities.tex#L10921)

*Returns*: An object of typebitset​::​reference such that(*this)[pos] == this->test(pos),
and such that(*this)[pos] = val is equivalent tothis->set(pos, val)[.](#34.sentence-1)

[35](#35)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/utilities.tex#L10932)

*Throws*: Nothing[.](#35.sentence-1)

[36](#36)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/utilities.tex#L10936)

*Remarks*: For the purpose of determining the presence of a data
race ([[intro.multithread]](intro.multithread "6.10.2 Multi-threaded executions and data races")), any access or update through the resulting
reference potentially accesses or modifies, respectively, the entire
underlying bitset[.](#36.sentence-1)

[🔗](#lib:to_ulong,bitset)

`constexpr unsigned long to_ulong() const;
`

[37](#37)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/utilities.tex#L10950)

*Returns*: x[.](#37.sentence-1)

[38](#38)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/utilities.tex#L10954)

*Throws*: overflow_error if the integral value x corresponding to the bits in *this cannot be represented as type unsigned long[.](#38.sentence-1)

[🔗](#lib:to_ullong,bitset)

`constexpr unsigned long long to_ullong() const;
`

[39](#39)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/utilities.tex#L10968)

*Returns*: x[.](#39.sentence-1)

[40](#40)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/utilities.tex#L10972)

*Throws*: overflow_error if the integral value x corresponding to the bits in *this cannot be represented as type unsigned long long[.](#40.sentence-1)

[🔗](#lib:to_string,bitset)

`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;
`

[41](#41)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/utilities.tex#L10990)

*Effects*: Constructs a string object of the appropriate type
and initializes it to a string of length N characters[.](#41.sentence-1)

Each character is determined by the value of its corresponding bit position in*this[.](#41.sentence-2)

Character position N - 1 corresponds to bit position zero[.](#41.sentence-3)

Subsequent decreasing character positions correspond to increasing bit
positions[.](#41.sentence-4)

Bit value zero becomes the character zero,
bit value one becomes the characterone[.](#41.sentence-5)

[42](#42)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/utilities.tex#L11003)

*Returns*: The created object[.](#42.sentence-1)

[🔗](#lib:count,bitset)

`constexpr size_t count() const noexcept;
`

[43](#43)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/utilities.tex#L11014)

*Returns*: A count of the number of bits set in*this[.](#43.sentence-1)

[🔗](#lib:size,bitset)

`constexpr size_t size() const noexcept;
`

[44](#44)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/utilities.tex#L11026)

*Returns*: N[.](#44.sentence-1)

[🔗](#lib:operator==,bitset)

`constexpr bool operator==(const bitset& rhs) const noexcept;
`

[45](#45)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/utilities.tex#L11037)

*Returns*: true if the value of each bit in*this equals the value of the corresponding bit in rhs[.](#45.sentence-1)

[🔗](#lib:test,bitset)

`constexpr bool test(size_t pos) const;
`

[46](#46)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/utilities.tex#L11050)

*Returns*: true if the bit at position pos in*this has the value one[.](#46.sentence-1)

[47](#47)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/utilities.tex#L11058)

*Throws*: out_of_range if pos does not correspond to a valid bit position[.](#47.sentence-1)

[🔗](#lib:all,bitset)

`constexpr bool all() const noexcept;
`

[48](#48)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/utilities.tex#L11070)

*Returns*: count() == size()[.](#48.sentence-1)

[🔗](#lib:any_(member),bitset)

`constexpr bool any() const noexcept;
`

[49](#49)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/utilities.tex#L11083)

*Returns*: count() != 0[.](#49.sentence-1)

[🔗](#lib:none,bitset)

`constexpr bool none() const noexcept;
`

[50](#50)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/utilities.tex#L11094)

*Returns*: count() == 0[.](#50.sentence-1)