std::is_void (3) - Linux Man Pages

std::is_void: std::is_void

NAME

std::is_void - std::is_void

Synopsis


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


Checks whether T is a void type. Provides the member constant value that is equal to true, if T is the type void, const void, volatile void, or const volatile void. Otherwise, value is equal to false.

Template parameters


T - a type to check


Helper variable template


template< class T > (since C++17)
inline constexpr bool is_void_v = is_void<T>::value;


Inherited from std::integral_constant

Member constants


value true if T is the type void (possibly cv-qualified) , 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_void : std::is_same<void, typename std::remove_cv<T>::type> {};

Example


// Run this code


  #include <iostream>
  #include <type_traits>


  int main()
  {
      std::cout << std::boolalpha;
      std::cout << std::is_void<void>::value << '\n';
      std::cout << std::is_void<int>::value << '\n';
  }

Output:


  true
  false

See also


is_array checks if a type is an array type
            (class template)
(C++11)


is_pointer checks if a type is a pointer type
            (class template)
(C++11)


is_enum checks if a type is an enumeration type
            (class template)
(C++11)


is_union checks if a type is an union type
            (class template)
(C++11)


is_class checks if a type is a non-union class type
            (class template)
(C++11)


is_function checks if a type is a function type
            (class template)
(C++11)


is_object checks if a type is an object type
            (class template)
(C++11)