std::is_fundamental (3) - Linux Manuals

std::is_fundamental: std::is_fundamental

NAME

std::is_fundamental - std::is_fundamental

Synopsis


Defined in header <type_traits>
template< class T > (since C++11)
struct is_fundamental;


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 > (since C++17)
inline constexpr bool is_fundamental_v = is_fundamental<T>::value;


Inherited from std::integral_constant

Member constants


value true if T is a fundamental type , false otherwise
         (public static member constant)
[static]

Member functions


              converts the object to bool, returns value
operator bool (public member function)


operator() returns value
              (public member function)
(C++14)

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
          // you can also use 'std::is_null_pointer<T>::value' instead in C++14
  > {};

Example


// Run this code


  #include <iostream>
  #include <type_traits>


  class A {};


  int main()
  {
      std::cout << std::boolalpha;
      std::cout << "A\t" << std::is_fundamental<A>::value << '\n';
      std::cout << "int\t" << std::is_fundamental<int>::value << '\n';
      std::cout << "int&\t" << std::is_fundamental<int&>::value << '\n';
      std::cout << "int*\t" << std::is_fundamental<int*>::value << '\n';
      std::cout << "float\t" << std::is_fundamental<float>::value << '\n';
      std::cout << "float&\t" << std::is_fundamental<float&>::value << '\n';
      std::cout << "float*\t" << std::is_fundamental<float*>::value << '\n';
  }

Output:


  A false

  int true

  int& false

  int* false

  float true

  float& false

  float* false

See also


is_compound checks if a type is a compound type
                (class template)
(C++11)


is_arithmetic checks if a type is an arithmetic type
                (class template)
(C++11)


is_void checks if a type is void
                (class template)
(C++11)


is_null_pointer checks if a type is std::nullptr_t
                (class template)
(C++14)