# std::is_void

From cppreference.com
< cpp‎ | types

Defined in header `<type_traits>` |  |
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` | 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 (C++11) | checks if a type is an array type (class template)
is_pointer (C++11) | checks if a type is a pointer type (class template)
is_enum (C++11) | checks if a type is an enumeration type (class template)
is_union (C++11) | checks if a type is an union type (class template)
is_class (C++11) | checks if a type is a non-union class type (class template)
is_function (C++11) | checks if a type is a function type (class template)
is_object (C++11) | checks if a type is an object type (class template)

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