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