std::is_volatile

From cppreference.com
< cpp‎ | types
 
 
Metaprogramming library
Type traits
Type categories
(C++11)
(C++11)
(C++11)
(C++11)
(C++11)
(C++11)
(C++11)
(C++11)
Type properties
(C++11)
is_volatile
(C++11)
(C++11)
(C++14)
(C++11)
(C++11)(until C++20)
(C++11)(deprecated in C++20)
(C++11)
Type trait constants
Metafunctions
(C++17)
Supported operations
Relationships and property queries
Type modifications
(C++11)(C++11)(C++11)
Type transformations
(C++11)(deprecated in C++23)
(C++11)(deprecated in C++23)
(C++11)
(C++11)
(C++17)

(C++11)(until C++20)(C++17)
Compile-time rational arithmetic
Compile-time integer sequences
 
Defined in header <type_traits>
template< class T >
struct is_volatile;
(since C++11)

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 is_volatile or is_volatile_v (since C++17) is undefined.

Template parameters

T - a type to check

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>

Possible implementation

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

Example

#include <iostream>
#include <type_traits>
 
int main() 
{
    std::cout << std::boolalpha;
    std::cout << std::is_volatile<int>::value << '\n';
    std::cout << std::is_volatile<volatile int>::value  << '\n';
}

Output:

false
true

See also

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