std::bitset<N>::reference

 

C++

Compiler support

Freestanding and hosted

Language

Standard library

Standard library headers

Named requirements

Feature test macros (C++20)

Language support library

Concepts library (C++20)

Metaprogramming library (C++11)

Diagnostics library

General utilities library

Strings library

Containers library

Iterators library

Ranges library (C++20)

Algorithms library

Numerics library

Localizations library

Input/output library

Filesystem library (C++17)

Regular expressions library (C++11)

Concurrency support library (C++11)

Execution support library (C++26)

Technical specifications

Symbols index

External libraries

 

Utilities library

Language support Type support (basic types, RTTI) Library feature-test macros (C++20) Dynamic memory management Program utilities Coroutine support (C++20) Variadic functions is_constant_evaluated (C++20) is_within_lifetime (C++26) initializer_list (C++11) source_location (C++20) Three-way comparison three_way_comparablethree_way_comparable_with (C++20)(C++20) strong_ordering (C++20) weak_ordering (C++20) partial_ordering (C++20) common_comparison_category (C++20) compare_three_way_result (C++20) compare_three_way (C++20) strong_order (C++20) weak_order (C++20) partial_order (C++20) compare_strong_order_fallback (C++20) compare_weak_order_fallback (C++20) compare_partial_order_fallback (C++20)   is_eqis_ltis_lteq (C++20)(C++20)(C++20)   is_neqis_gtis_gteq (C++20)(C++20)(C++20)

General utilities Date and time Function objects Formatting library (C++20)   bitset hash (C++11) Relational operators (deprecated in C++20) rel_ops::operator!=rel_ops::operator>    rel_ops::operator<=rel_ops::operator>= Integer comparison functions cmp_equalcmp_lesscmp_less_than (C++20)(C++20)(C++20)   cmp_not_equalcmp_greatercmp_greater_than (C++20)(C++20)(C++20) in_range (C++20) Swap and type operations swap ranges::swap (C++20) exchange (C++14) declval (C++11) to_underlying (C++23) forward (C++11) forward_like (C++23) move (C++11) move_if_noexcept (C++11) as_const (C++17) Common vocabulary types pair tuple (C++11) optional (C++17) any (C++17) variant (C++17) tuple_size (C++11) tuple_element (C++11) apply (C++17) make_from_tuple (C++17) expected (C++23) Elementary string conversions to_chars (C++17) from_chars (C++17) chars_format (C++17) to_chars_result (C++17) from_chars_result (C++17)

 

std::bitset

Member types
bitset::reference
Member functions
bitset::bitset
bitset::operator==bitset::operator!= (until C++20)
Element access
bitset::operator[]
bitset::test
bitset::allbitset::anybitset::none (C++11)
bitset::count
Capacity
bitset::size
Modifiers
bitset::operator&=bitset::operator|=bitset::operator^=bitset::operator~
bitset::operator<<=bitset::operator>>=bitset::operator<<bitset::operator>>
bitset::set
bitset::reset
bitset::flip
Conversions
bitset::to_string
bitset::to_ulong
bitset::to_ullong (C++11)
Non-member functions
operator&operator|operator^	operator<<operator>>
Helper classes
std::hash (C++11)

 

class reference;

The std::bitset class includes std::bitset::reference as a publicly-accessible nested class. This class is used as a proxy object to allow users to interact with individual bits of a bitset, since standard C++ types (like references and pointers) are not built with enough precision to specify individual bits.

The primary use of std::bitset::reference is to provide an lvalue that can be returned from operator[].

Any reads or writes to a bitset that happen via a std::bitset::reference potentially read or write to the entire underlying bitset.

Member functions

(constructor)	constructs the reference. Accessible only to std::bitset itself (private member function)
(destructor)	destroys the reference (public member function)
operator=	assigns a bool to the referenced bit (public member function)
operator bool	returns the referenced bit (public member function)
operator~	returns inverted referenced bit (public member function)
flip	flips the referenced bit (public member function)

std::bitset<N>::reference::~reference

~reference();		(constexpr since C++23)

Destroys the reference.

std::bitset<N>::reference::operator=

	(1)
reference& operator=( bool x );			(until C++11)
reference& operator=( bool x ) noexcept;			(since C++11) (constexpr since C++23)
		(2)
reference& operator=( const reference& x );				(until C++11)
reference& operator=( const reference& x ) noexcept;				(since C++11) (constexpr since C++23)

Assigns a value to the referenced bit.

Parameters

x

-

value to assign

Return value

*this

std::bitset<N>::reference::operator bool

operator bool() const;		(until C++11)
operator bool() const noexcept;		(since C++11) (constexpr since C++23)

Returns the value of the referenced bit.

Parameters

(none)

Return value

The referenced bit.

std::bitset<N>::reference::operator~

bool operator~() const;		(until C++11)
bool operator~() const noexcept;		(since C++11) (constexpr since C++23)

Returns the inverse of the referenced bit.

Parameters

(none)

Return value

The inverse of the referenced bit.

std::bitset<N>::reference::flip

reference& flip();		(until C++11)
reference& flip() noexcept;		(since C++11) (constexpr since C++23)

Inverts the referenced bit.

Parameters

(none)

Return value

*this

Example

Run this code

#include <bitset>
#include <iostream>
 
int main()
{
    std::bitset<4> bs{0b1110};
    std::bitset<4>::reference ref = bs[2];
 
    auto info = [&](int id)
    {
        std::cout << id << ") bs: " << bs << "; ref bit: " << ref << '\n';
    };
 
    info(1);
    ref = false;
    info(2);
    ref = true;
    info(3);
    ref.flip();
    info(4);
    ref = bs[1]; // operator=( const reference& x )
    info(5);
 
    std::cout << "6) ~ref bit: " << ~ref << '\n';
}

Output:

1) bs: 1110; ref bit: 1
2) bs: 1010; ref bit: 0
3) bs: 1110; ref bit: 1
4) bs: 1010; ref bit: 0
5) bs: 1110; ref bit: 1
6) ~ref bit: 0

See also

operator[]

accesses specific bit (public member function)