std::is_volatile

template< class T >
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.

The behavior of a program that adds specializations for std::is_volatile or std::is_volatile_v is undefined.

Template parameters

Helper variable template

template< class T >
inline constexpr bool is_volatile_v = is_volatile<T>::value;

Possible implementation

template<class T> struct is_volatile : std::false_type {};
template<class T> struct is_volatile<volatile T> : std::true_type {};

Example

#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