std::vector<bool>::reference

 

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class reference;

The std::vector<bool> specialization defines std::vector<bool>::reference as a publicly-accessible nested class. std::vector<bool>::reference proxies the behavior of references to a single bit in std::vector<bool>.

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

Any reads or writes to a vector that happen via a std::vector<bool>::reference potentially read or write to the entire underlying vector.

Member functions

(constructor)	constructs the reference. Accessible only to std::vector<bool> itself (public 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)
flip	flips the referenced bit (public member function)

std::vector<bool>::reference::~reference

~reference();		(until C++20)
constexpr ~reference();		(since C++20)

Destroys the reference.

std::vector<bool>::reference::operator=

	(1)
reference& operator=( bool x );			(until C++11)
reference& operator=( bool x ) noexcept;			(since C++11) (until C++20)
constexpr reference& operator=( bool x ) noexcept;			(since C++20)
		(2)
reference& operator=( const reference& x );				(until C++11)
reference& operator=( const reference& x ) noexcept;				(since C++11) (until C++20)
constexpr reference& operator=( const reference& x ) noexcept;				(since C++20)
constexpr const reference& operator=( bool x ) const noexcept;			(3)	(since C++23)

Assigns a value to the referenced bit.

Parameters

x

-

value to assign

Return value

*this

std::vector<bool>::reference::operator bool

operator bool() const;		(until C++11)
operator bool() const noexcept;		(since C++11) (until C++20)
constexpr operator bool() const noexcept;		(since C++20)

Returns the value of the referenced bit.

Parameters

(none)

Return value

The referenced bit.

std::vector<bool>::reference::flip

void flip();		(until C++11)
void flip() noexcept;		(since C++11) (until C++20)
constexpr void flip() noexcept;		(since C++20)

Inverts the referenced bit.

Parameters

(none)

Return value

(none)

See also

operator[]	access specified element (public member function of std::vector<T,Allocator>)
swap [static]	swaps two std::vector<bool>::references (public static member function)

External links

"Effective Modern C++" by Scott Meyers (2015), Chapter 2, Item 6: "Use the explicitly typed initializer idiom when auto deduces undesired types." (p.43-46) — describes a possible misuse of the proxy class std::vector<bool>::reference).