is_volatile template in C++

The std::is_volatile template of C++ STL is used to check whether the type is a volatile-qualified or not. It returns a boolean value showing the same.

Syntax:

template < class T > struct is_volatile;

Parameter: This template contains single parameter T (Trait class) to check whether T is a volatile-qualified type or not.

Return Value: This template returns a boolean value as shown below:

• True: if the type is a volatile-qualified.
• False: if the type is a non-volatile-qualified.

Below programs illustrate the std::is_volatile template in C++ STL:

Program 1:

// C++ program to illustrate
// std::is_volatile template

#include <iostream>
#include <type_traits>
using namespace std;

// main program
int main()
{
    cout << boolalpha;
    cout << "is_volatile:"
         << '\n';
    cout << "volatile int:"
         << is_volatile<volatile int>::value
         << '\n';
    cout << "volatile void:"
         << is_volatile<volatile void>::value
         << '\n';
    cout << "int:"
         << is_volatile<int>::value
         << '\n';
    cout << "char:"
         << is_volatile<char>::value
         << '\n';

    return 0;
}

Output:

is_volatile:
volatile int:true
volatile void:true
int:false
char:false

Program 2:

// C++ program to illustrate
// std::is_volatile template

#include <iostream>
#include <type_traits>
using namespace std;

// main program
int main()
{
    cout << boolalpha;
    cout << "is_volatile:"
         << '\n';
    cout << "double:"
         << is_volatile<double>::value
         << '\n';
    cout << "float:"
         << is_volatile<float>::value
         << '\n';
    cout << "const volatile void:"
         << is_volatile<const volatile void>::value
         << '\n';

    return 0;
}

Output:

is_volatile:
double:false
float:false
const volatile void:true

Program 3:

// C++ program to illustrate
// std::is_volatile template

#include <iostream>
#include <type_traits>
using namespace std;

// main program
int main()
{
    cout << boolalpha;
    cout << "is_volatile:"
         << '\n';
    cout << "volatile double:"
         << is_volatile<volatile double>::value
         << '\n';
    cout << "volatile float:"
         << is_volatile<volatile float>::value
         << '\n';
    cout << "bool:"
         << is_volatile<bool>::value
         << '\n';
    cout << "volatile char:"
         << is_volatile<volatile char>::value
         << '\n';

    return 0;
}

Output:

is_volatile:
volatile double:true
volatile float:true
bool:false
volatile char:true