std::is_void
Defined in header <type_traits>
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template< class T > struct is_void; |
(since C++11) | |
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 > inline constexpr bool is_void_v = is_void<T>::value; |
(since C++17) | |
Inherited from std::integral_constant
Member constants
value [static] |
true if T is the type void (possibly cv-qualified) , false otherwise (public static member constant) |
Member functions
operator bool |
converts the object to bool, returns value (public member function) |
operator() (C++14) |
returns value (public member function) |
Member types
Type | Definition |
value_type
|
bool
|
type
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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
(C++11) |
checks if a type is an array type (class template) |
(C++11) |
checks if a type is a pointer type (class template) |
(C++11) |
checks if a type is an enumeration type (class template) |
(C++11) |
checks if a type is an union type (class template) |
(C++11) |
checks if a type is a non-union class type (class template) |
(C++11) |
checks if a type is a function type (class template) |
(C++11) |
checks if a type is an object type (class template) |