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std::is_rvalue_reference

Defined in header `<type_traits>`
template< class T > struct is_rvalue_reference;		(since C++11)

Checks whether T is an rvalue reference type. Provides the member constant value which is equal to true, if T is an rvalue reference type. Otherwise, value is equal to false.

The behavior of a program that adds specializations for is_rvalue_reference or is_rvalue_reference_v (since C++17) is undefined.

Template parameters

a type to check

Helper variable template

template< class T >
inline constexpr bool is_rvalue_reference_v = is_rvalue_reference<T>::value;

(since C++17)

Inherited from std::integral_constant

Member constants

value

[static]

true if T is an rvalue reference type, false otherwise
(public static member constant)

Member functions

operator bool	converts the object to bool, returns `value` (public member function)
operator() (C++14)	returns `value` (public member function)

Member types

Type	Definition
`value_type`	bool
`type`	std::integral_constant<bool, value>

Possible implementation

template<class T> struct is_rvalue_reference : std::false_type {};
template<class T> struct is_rvalue_reference<T&&> : std::true_type {};

Example

#include <type_traits>
 
class A {};
 
int main()
{
    static_assert(!std::is_rvalue_reference_v<A>);
    static_assert(!std::is_rvalue_reference_v<A&>);
    static_assert( std::is_rvalue_reference_v<A&&>);
    static_assert(!std::is_rvalue_reference_v<int>);
    static_assert(!std::is_rvalue_reference_v<int&>);
    static_assert( std::is_rvalue_reference_v<int&&>);
}

is_lvalue_reference (C++11)	checks if a type is an lvalue reference (class template)
is_reference (C++11)	checks if a type is either an lvalue reference or rvalue reference (class template)