NAME¶

std::is_volatile - std::is_volatile

Synopsis¶

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

std::is_volatile is a UnaryTypeTrait.

If T is a volatile-qualified type (that is, volatile, or const volatile), provides
the member constant value equal to true. For any other type, value is false.

If the program adds specializations for std::is_volatile or std::is_volatile_v, the
behavior is undefined.

Template parameters¶

T - a type to check

Helper variable template

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

Inherited from std::integral_constant

Member constants¶

value true if T is a volatile-qualified type, 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_volatile : std::false_type {};
template<class T> struct is_volatile<volatile T> : std::true_type {};

Example¶

// Run this code

#include <type_traits>
#include <valarray>

static_assert(!std::is_volatile_v<int>);
static_assert(std::is_volatile_v<volatile int>);
static_assert(std::is_volatile_v<volatile const int>);
static_assert(std::is_volatile_v<volatile std::valarray<float>>);
static_assert(!std::is_volatile_v<std::valarray<volatile float>>);

int main() {}

See also¶

is_const checks if a type is const-qualified
(C++11) (class template)