std::is_volatile

 

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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 constvolatile), 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 > constexprbool 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>

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<volatileint>); static_assert(std::is_volatile_v<volatileconstint>); static_assert(std::is_volatile_v<volatilestd::valarray<float>>); static_assert(!std::is_volatile_v<std::valarray<volatilefloat>>);   int main(){}

See also

is_const (C++11)

checks if a type is const-qualified (class template)