if I have a class and I defined a destructor for it (the destructor itself sends messages to the system and does not handle memory deallocation) .
if dynamically allocated an object of this class and called "delete" - will the memory still be deallocated although the destructor does not have any line that deallocated memory?
The destructor is only responsible for deallocating or freeing whatever resources you acquired in the constructor, i.e. whatever resources your class acquired, it should free.
new and delete occurs outside your class, so your class is not responsible for doing anything with that.
So the answer to your question is 'yes'. New handles the allocation and delete handles the deallocation (not the destructor). This is a simplified view, but hey, it works.
Originally Posted by Adak
but the destructor will still be called when using delete , right?
Yes.
On the other hand, if the class has explicitly allocated memory (e.g. in a constructor) it needs to be released somewhere. If the destructor (or some other member function of the class) does not explicitly release it, that memory will never be released.
This is independent of whether an instance of the class is explicitly allocated. The sequence "x = new X; delete x;" will leak if X allocates memory for the object x and it is not cleaned up.
The same goes for any other global resource (file handles, mutexes, etc) that the class manages.
