std::vector<bool, Alloc>::reference

 

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std::vector<bool>

Member types
vector<bool>::reference
Member functions
vector::vector vector::~vector vector::operator= vector::assign vector::assign_range (C++23) vector::get_allocator Element access vector::operator[] vector::at vector::front vector::back Iterators vector::beginvector::cbegin (C++11) vector::endvector::cend (C++11) vector::rbeginvector::crbegin (C++11) vector::rendvector::crend (C++11)	Capacity vector::empty vector::size vector::max_size vector::capacity vector::resize vector::reserve vector::shrink_to_fit (DR*) Modifiers vector::clear vector::erase vector::insert vector::insert_range (C++23) vector::append_range (C++23) vector::emplace (C++11) vector::emplace_back (C++11) vector::push_back vector::pop_back vector::swap vector<bool>::flip vector<bool>::swap
Non-member functions
operator==operator<=> (C++20) swap(std::vector<bool>) erase(std::vector<bool>)erase_if(std::vector<bool>) (C++20)(C++20)	operator!=operator<operator>operator<=operator>= (until C++20)(until C++20)(until C++20)(until C++20)(until C++20)
Helper classes
hash<std::vector<bool>> (C++11)
Deduction guides(C++17)

 

class reference;

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

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

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

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)
flip	flips the referenced bit (public member function)

std::vector<bool, Alloc>::reference::reference

reference(const reference&)=default;		(since C++11) (constexpr since C++20)

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

Other constructors can only be accessed by std::vector<bool, Alloc>.

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

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

Destroys the reference.

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

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

Assigns a value to the referenced bit.

The const operator= enables std::vector<bool,Alloc>::iterator to satisfy output_iterator.

(since C++23)

Parameters

x

-

value to assign

Return value

*this

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

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

Returns the value of the referenced bit.

Return value

The referenced bit.

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

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

Inverts the referenced bit.

Helper classes

std::formatter<std::vector<bool, Alloc>::reference>

template<class T, class CharT >   requires /*is-vector-bool-reference*/<T> struct formatter<T, CharT>;		(since C++23)

Specializes the std::formatter for std::vector<bool, Alloc>::reference. The specialization uses std::formatter<bool, CharT> as its underlying formatter (denoted as underlying_) where the referenced bit is converted to bool to be formatted.

The exposition-only constant /*is-vector-bool-reference*/<T> is true if and only if T denotes the type std::vector<bool, Alloc>::reference for some type Alloc and std::vector<bool, Alloc> is not a program-defined specialization.

Member functions

template<class ParseContext > constexpr ParseContext::iterator parse( ParseContext& ctx );	(1)	(since C++23)
template<class FormatContext > FormatContext::iterator format(const T& r, FormatContext& ctx )const;	(2)	(since C++23)

1) Equivalent to return underlying_.parse(ctx);.

2) Equivalent to return underlying_.format(r, ctx);.

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).