std::is_rvalue_reference
From cppreference.com
| Defined in header <type_traits>
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| template< class T > struct is_rvalue_reference; |
(since C++11) | |
Checks whether T is a rvalue reference type. Provides the member constant value which is equal to true, if T is a rvalue reference type. Otherwise, value is equal to false.
Contents |
[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
| 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
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type
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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
Run this code
#include <iostream> #include <type_traits> class A {}; int main() { std::cout << std::boolalpha; std::cout << std::is_rvalue_reference<A>::value << '\n'; std::cout << std::is_rvalue_reference<A&>::value << '\n'; std::cout << std::is_rvalue_reference<A&&>::value << '\n'; std::cout << std::is_rvalue_reference<int>::value << '\n'; std::cout << std::is_rvalue_reference<int&>::value << '\n'; std::cout << std::is_rvalue_reference<int&&>::value << '\n'; }
Output:
false false true false false true
[edit] See also
| (C++11) |
checks if a type is lvalue reference (class template) |
| (C++11) |
checks if a type is either lvalue reference or rvalue reference (class template) |