Question

I have this code :

 Derived **args = new Derived*[2];
 args[0] = new Derived();
 args[0]->setname("BLABLA \n");
 cout << args[0]->getname();
 delete args[0];

 args[1] = new Derived();
 args[1]->setname("BLABLABLA\n");
 cout << args[1]->getname();
 delete args[1];
 delete [] args;

Is delete [] args required? And why?

Also, what does Derived **args = new Derived*[2] really do? Does it allocate space for two pointers to Derived? If so, then how can I dynamically create an array that contains 2 objects of type Derived on the heap?

Answer 1

Is delete [] args required? And why?

Yes it is. It frees the memory allocated by new Derived*[2].

Also, what does Derived **args = new Derived*[2] really do?

It allocates space for two pointers to Derived. It does not allocate space for any Derived objects.

how can I dynamically create an array that contains 2 objects of type Derived on the heap?

Just remove one level of indirection:

 Derived *args = new Derived[2];

 args[0].setname("BLABLA \n");
 cout << args[0].getname();

 args[1].setname("BLABLABLA\n");
 cout << args[1].getname();

 delete [] args;

But bear in mind that arrays and polymorphism don’t mix. For details, see How to make an array with polymorphism in C++?