Should delete necessarily be the last statement in a destructor?

Question

I ran into this piece of code in a (fairly well respected) book. (Note: "head" is a pointer of type Element)

Stack::~Stack(){
  while(head){
    Element *next = head->next;
    delete head;
    head = next;
   }
    return;
}

From my understanding, the delete keyword de-allocates the memory assigned to a pointer. How is it that the author has used the pointer in the next line, immediately after de-allocating it? This confused me a bit. Am I missing something really obvious?

Answer 1

How is it that the author has used the pointer in the next line, immediately after de-allocating it?

The author is reassigning the pointer to the next element.

The delete is deallocating the memory pointed to by head. It doesn't "deallocate" the pointer itself - the pointer will still exist and being usable.

head = next then makes head point to a different chunk of memory (the chunk pointed to by next). The memory that was deleted is never used again, so there is no issue.