Skip site navigation (1)Skip section navigation (2)

FreeBSD Manual Pages

  
 
  

home | help 
std::is_void(3)		      C++ Standard Libary	       std::is_void(3)

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.

	  The behavior of a program that adds specializations for is_void
	  or is_void_v
	  (since C++17)	is undefined.

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
	  [static] (public static member constant)

Member functions
	  operator bool	converts the object to bool, returns value
			(public	member function)
	  operator()	returns	value
	  (C++14)	(public	member function)

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::re-
       move_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
	  (C++11)     (class template)
	  is_pointer  checks if	a type is a pointer type
	  (C++11)     (class template)
	  is_enum     checks if	a type is an enumeration type
	  (C++11)     (class template)
	  is_union    checks if	a type is an union type
	  (C++11)     (class template)
	  is_class    checks if	a type is a non-union class type
	  (C++11)     (class template)
	  is_function checks if	a type is a function type
	  (C++11)     (class template)
	  is_object   checks if	a type is an object type
	  (C++11)     (class template)

http://cppreference.com		  2022.07.31		       std::is_void(3)

Want to link to this manual page? Use this URL:
<https://man.freebsd.org/cgi/man.cgi?query=std::is_void&sektion=3&manpath=FreeBSD+Ports+15.0>

home | help