Pure virtual destructor

Did you know that a destructor can be pure virtual? It can be defined as such, but it still needs a body declaration. It is a way of making a class abstract (instances of it cannot be created) without having to make any pure virtual methods. So use it if you have a base class that you don’t want users to instantiate but you have no other candidates for pure virtual specifier 🙂

Additional discussion of this topic at Geeks for Geeks: Pure virtual destructor in C++.

Complete listing:

class base
{
public:
	virtual ~base() = 0;
};

base::~base() {}

class derived : public base
{
public:
	virtual ~derived() {}
};

int main(int argc, char** argv)
{
	//base b; // Compile error: Variable type 'base' is an abstract class
	derived d;

	return 1;
}