std::is_reference
From cppreference.com
| Defined in header <type_traits>
|
||
| template< class T > struct is_reference; |
(since C++11) | |
If T is a reference type (lvalue reference or rvalue reference), provides the member constant value equal true. For any other type, value is false.
Template parameters
| T | - | a type to check |
Helper variable template
| template< class T > inline constexpr bool is_reference_v = is_reference<T>::value; |
(since C++17) | |
Inherited from std::integral_constant
Member constants
| value [static] |
true if T is a 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_reference : std::false_type {}; template <class T> struct is_reference<T&> : std::true_type {}; template <class T> struct is_reference<T&&> : std::true_type {}; |
Example
Run this code
#include <iostream> #include <type_traits> class A {}; int main() { std::cout << std::boolalpha; std::cout << std::is_reference<A>::value << '\n'; std::cout << std::is_reference<A&>::value << '\n'; std::cout << std::is_reference<A&&>::value << '\n'; std::cout << std::is_reference<int>::value << '\n'; std::cout << std::is_reference<int&>::value << '\n'; std::cout << std::is_reference<int&&>::value << '\n'; }
Output:
false true true false true true
See also
| (C++11) |
checks if a type is a lvalue reference (class template) |
| (C++11) |
checks if a type is a rvalue reference (class template) |