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std::is_volatile

From cppreference.com
< cpp‎ | types
 
 
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Type properties
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is_volatile
(C++11)
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Defined in header <type_traits>
template< class T >
struct is_volatile;
(since C++11)

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.

Contents

[edit] Template parameters

T - a type to check

[edit] Helper variable template

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

Inherited from std::integral_constant

Member constants

value
[static]
true if T is a volatile-qualified type, 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>

[edit] Possible implementation

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

[edit] 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() {}

[edit] See also

(C++11)
checks if a type is const-qualified
(class template) [edit]