std::has_virtual_destructor in C++ with Examples

The std::has_virtual_destructor of C++ STL is used to check whether the given type T has a virtual destructor or not. It returns the boolean value either true or false. Below is the syntax for the same:
Header File: 

#include<type_traits>

Syntax: 

template
  <class T>
  struct has_virtual_destructor;

Parameter: The template std::has_virtual_destructor accepts a single parameter T (Trait class) to check whether T has a virtual destructor or not.
Return Values: 

• True: If virtual destructor present.
• False: If virtual destructor not present.

Below programs illustrate the std::has_virtual_destructor template in C++ STL:
Program 1:

CPP14

// C++ program to illustrate
// has_virtual_destructor example

#include <bits/stdc++.h>
#include <type_traits>
using namespace std;

struct gfg1 {
};
struct gfg2 {
    virtual ~gfg2() {}
};
struct gfg3 : gfg2 {
};

// Driver Code
int main()
{
    cout << boolalpha;
    cout << "has_virtual_destructor:"
         << endl;
    cout << "int: "
         << has_virtual_destructor<int>::value
         << endl;
    cout << "gfg1: "
         << has_virtual_destructor<gfg1>::value
         << endl;
    cout << "gfg2: "
         << has_virtual_destructor<gfg2>::value
         << endl;
    cout << "gfg3: "
         << has_virtual_destructor<gfg3>::value
         << endl;

    return 0;
}

Output:

has_virtual_destructor:
int: false
gfg1: false
gfg2: true
gfg3: true

Program 2:

CPP14

// C++ program to illustrate
// has_virtual_destructor example

#include <bits/stdc++.h>
#include <type_traits>
using namespace std;

struct gfg1 {
    virtual ~gfg1() {}
};
struct gfg2 {
};
struct gfg3 : gfg1 {
};

// Driver Code
int main()
{
    cout << boolalpha;
    cout << "has_virtual_destructor:"
         << endl;
    cout << "int: "
         << has_virtual_destructor<int>::value
         << endl;
    cout << "gfg1: "
         << has_virtual_destructor<gfg1>::value
         << endl;
    cout << "gfg2: "
         << has_virtual_destructor<gfg2>::value
         << endl;
    cout << "gfg3: "
         << has_virtual_destructor<gfg3>::value
         << endl;

    return 0;
}

Output:

has_virtual_destructor:
int: false
gfg1: true
gfg2: false
gfg3: true

Reference: http://www.cplusplus.com/reference/type_traits/has_virtual_destructor/