< cpp‎ | types
Metaprogramming library
Type traits
Type categories
Type properties
(C++11)(until C++20)
(C++11)(deprecated in C++20)
Type trait constants
Supported operations
Relationships and property queries
Type modifications
Type transformations
(C++11)(deprecated in C++23)
(C++11)(deprecated in C++23)

(C++11)(until C++20)(C++17)
Compile-time rational arithmetic
Compile-time integer sequences
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.


[edit] Template parameters

T - a type to check

[edit] 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

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)
returns value
(public member function)

Member types

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

[edit] Possible implementation

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

[edit] Example

#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&&> );

[edit] See also

checks if a type is an lvalue reference
(class template) [edit]
checks if a type is either an lvalue reference or rvalue reference
(class template) [edit]