Thread: MSVC 2003 Debugging delete

I am not sure what I am doing incorrectly but when I step through with the debugger after selecting "delete head" it still retains its original address:

Code:

....
void DeleteAllNodes()
{
	int test=0;
	current =  head;

	if(!head)
		return;

	if(WC.bDebug)
	{
		fprintf(fpDebug, "\nDeleteAllNodes from head to tail.\n");
	}
	while(1)
	{
		temp = head;
		if(head->next == 0)
			break;
		head = head->next;

		if(WC.bDebug)
		{
			fprintf(fpDebug, "Delete %4d current = %9p prev = %9p\n", test, temp, temp->prev);
			fflush(fpDebug);
		}
		delete temp;
		test+=1;
	}

	if(WC.bDebug)
	{
		fprintf(fpDebug, "Delete %4d head    = %9p prev = %9p\n", test, temp, temp->prev);
		fflush(fpDebug);
	}
	delete head; 
	return;  // head still has its original address!!!
}

The node head is not set to zero.

This really screws me up in my next call because I use head to control my creation of the new linked list.

Code:

		if (! head )
		{
			head = new node;
			tail = current = head;	// set current and tail = to head
			current->next = 0;		// set next node to zero.
			current->prev = 0;		// set prev node to zero or possibly set to tail!!!

Do you see anything wrong with how I am calling delete?

It might still contain an address, but you'd be hosed if you tried to dereference it.

delete head;
head = NULL;
If you want to be extra safe.

It's the same with free() in C, free(p) does NOT set p to NULL.

What about

Code:

while ( head != NULL ) {
  temp = head;
  head = head->next;
  delete temp;
}

Ensures head becomes NULL, and saves all the special case logic you have.

And why does temp appear to be a global / class variable, and not a local to the function / block?
And what does 'current' do ?

Well I'm bad, current is just hanging around waiting for something to do! Yeah I do think I need to clean this up a bit!