std::is_rvalue_reference

 

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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

T

-

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

Run this code

#include <type_traits>
 
class A {};
 
int main()
{
    static_assert( not std::is_rvalue_reference_v<A> );
    static_assert( not std::is_rvalue_reference_v<A&> );
    static_assert(     std::is_rvalue_reference_v<A&&> );
    static_assert( not std::is_rvalue_reference_v<int> );
    static_assert( not std::is_rvalue_reference_v<int&> );
    static_assert(     std::is_rvalue_reference_v<int&&> );
}

See also

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