std::bitset<N>::reference

 

C++

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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 l-value 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();		(until C++23)
constexpr ~reference();		(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) (until C++23)
constexpr reference& operator=( bool x ) noexcept;			(since C++23)
		(2)
reference& operator=( const reference& x );				(until C++11)
reference& operator=( const reference& x ) noexcept;				(since C++11) (until C++23)
constexpr reference& operator=( const reference& x ) noexcept;				(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) (until C++23)
constexpr operator bool() const noexcept;		(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) (until C++23)
constexpr bool operator~() const noexcept;		(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) (until C++23)
constexpr reference& flip() noexcept;		(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 ref = bs[2];
 
    auto info = [&](int n) {
        std::cout << n << ") 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)