std::is_void (3) - Linux Manuals

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