Question

The C++ specification says the default destructor deletes all non-static members. Nevertheless, I can’t manage to achieve that.

I have this:

class N {
public:
    ~N() {
        std::cout << "Destroying object of type N";
    }
};

class M {
public:
    M() {
        n = new N;
    }
//  ~M() { //this should happen by default
//      delete n;
//  }
private:
    N* n;
};

Then this should print the given message, but it doesn’t:

M* m = new M();
delete m; //this should invoke the default destructor

Answer 1

What makes you think the object n points to should be deleted by default? The default destructor destroys the pointer, not what it’s pointing to.

Edit: I’ll see if I can make this a little more clear.

If you had a local pointer, and it went out of scope, would you expect the object it points to to be destroyed?

{
    Thing* t = new Thing;

    // do some stuff here

    // no "delete t;"
}

The t pointer is cleaned up, but the Thing it points to is not. This is a leak. Essentially the same thing is happening in your class.