Defined in header <type_traits> | ||
---|---|---|
template< class T > struct is_lvalue_reference; | (since C++11) |
Checks whether T
is a lvalue reference type. Provides the member constant value
which is equal to true
, if T
is a lvalue reference type. Otherwise, value
is equal to false
.
T | - | a type to check |
template< class T > inline constexpr bool is_lvalue_reference_v = is_lvalue_reference<T>::value; | (since C++17) |
value
[static] | true if T is an lvalue reference type , false otherwise (public static member constant) |
operator bool | converts the object to bool , returns value (public member function) |
operator()
(C++14) | returns value (public member function) |
Type | Definition |
---|---|
value_type | bool |
type | std::integral_constant<bool, value> |
template<class T> struct is_lvalue_reference : std::false_type {}; template<class T> struct is_lvalue_reference<T&> : std::true_type {}; |
#include <iostream> #include <type_traits> class A {}; int main() { std::cout << std::boolalpha; std::cout << std::is_lvalue_reference<A>::value << '\n'; std::cout << std::is_lvalue_reference<A&>::value << '\n'; std::cout << std::is_lvalue_reference<A&&>::value << '\n'; std::cout << std::is_lvalue_reference<int>::value << '\n'; std::cout << std::is_lvalue_reference<int&>::value << '\n'; std::cout << std::is_lvalue_reference<int&&>::value << '\n'; }
Output:
false true false false true false
(C++11) | checks if a type is either a lvalue reference or rvalue reference (class template) |
(C++11) | checks if a type is a rvalue reference (class template) |
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