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