std::bitset<N>::reference

 

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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 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 (public member function)
(destructor)	destroys the reference (public member function)
operator=	assigns a value 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( const reference& ) = default;		(since C++11) (constexpr since C++23)

Constructs the reference from another reference. The copy constructor is implicitly declared.(until C++11)

Other constructors can only be accessed by std::bitset.

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

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

Destroys the reference.

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

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

Returns the value of the referenced bit.

Return value

The referenced bit.

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

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

Returns the inverse of the referenced bit.

Return value

The inverse of the referenced bit.

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

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

Inverts the referenced bit.

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)