| Defined in header <type_traits> | ||
|---|---|---|
template< class T > struct is_fundamental; | (since C++11) |
If T is a fundamental type (that is, arithmetic type, void, or nullptr_t), 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 > constexpr bool is_fundamental_v = is_fundamental<T>::value; | (since C++17) |
Inherited from std::integral_constant
Member constants
| value [static] | true if T is a fundamental 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_fundamental
: std::integral_constant<
bool,
std::is_arithmetic<T>::value ||
std::is_void<T>::value ||
std::is_same<std::nullptr_t, typename std::remove_cv<T>::type>::value
> {}; |
Example
#include <iostream>
#include <type_traits>
class A {};
int main()
{
std::cout << std::boolalpha;
std::cout << std::is_fundamental<A>::value << '\n';
std::cout << std::is_fundamental<int>::value << '\n';
std::cout << std::is_fundamental<int&>::value << '\n';
std::cout << std::is_fundamental<int*>::value << '\n';
std::cout << std::is_fundamental<float>::value << '\n';
std::cout << std::is_fundamental<float&>::value << '\n';
std::cout << std::is_fundamental<float*>::value << '\n';
}Output:
false true false false true false false
See also
| (C++11) | checks if a type is compound type (class template) |
| (C++11) | checks if a type is arithmetic type (class template) |
| (C++11) | checks if a type is void (class template) |
| std::experimental::is_fundamental_v
(library fundamentals TS) | variable template alias of std::is_fundamental::value (variable template) |
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