std::is_lvalue_reference
From cppreference.com
| Defined in header <type_traits>
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template< class T >
struct is_lvalue_reference;
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(since C++11) | |
std::is_lvalue_reference is a UnaryTypeTrait.
Checks whether T is an lvalue reference type. Provides the member constant value which is equal to true, if T is an lvalue reference type. Otherwise, value is equal to false.
If the program adds specializations for std::is_lvalue_reference or std::is_lvalue_reference_v, the behavior is undefined.
Template parameters
| T | - | a type to check |
Helper variable template
template< class T >
constexpr bool is_lvalue_reference_v = is_lvalue_reference<T>::value;
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(since C++17) | |
Inherited from std::integral_constant
Member constants
value [static] |
true if T is an lvalue 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
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bool
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type
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std::integral_constant<bool, value>
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Possible implementation
template<class T> struct is_lvalue_reference : std::false_type {};
template<class T> struct is_lvalue_reference<T&> : std::true_type {};
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Example
Run this code
#include <type_traits>
class A {};
static_assert(std::is_lvalue_reference_v<A> == false);
static_assert(std::is_lvalue_reference_v<A&> == true);
static_assert(std::is_lvalue_reference_v<A&&> == false);
static_assert(std::is_lvalue_reference_v<int> == false);
static_assert(std::is_lvalue_reference_v<int&> == true);
static_assert(std::is_lvalue_reference_v<int&&> == false);
int main() {}
See also
(C++11) |
checks if a type is either an lvalue reference or rvalue reference (class template) |
(C++11) |
checks if a type is an rvalue reference (class template) |