Earlier in this book we made the point that, when you delete a resource, you should set the pointer to nullptr and you should check a pointer before using it to see if it is nullptr. This is so that you do not call a pointer to memory for an object that has been deleted: a dangling pointer.
There are situations when a dangling pointer can occur by design. For example, a parent object may create child objects that have a back pointer to the parent so that the child has access to the parent. (An example of this is a window that creates child controls; it is often useful for the child controls to have access to the parent window.) The problem with using a shared pointer in this situation is that the parent will have ...
