C++ Deleting a node in Queue

Question

Problem1: Deleting in a node in a list > 3

Description:

Deletion of the sixth node in a list of seven, results in a print of only the first and last node.

Available Node Pointers: next, prev, data

Function to delete the specified node is in the LinkedList.cpp Name: DeleteNode.

Function that traverses through the list to print the nodes is in main.cpp Name: PrintAllNodes

Possible Solution: Being able to access Current->prev_ in main when traversing to print the nodes.

Code:

void LinkedList::DeleteNode( Node* node )
{
    Node *Current = first_; // I want this to be my only Node Ptr Varaible Declaration.
    if ( NULL == first_ )
     std::cout << "Cannot delete from an empty list: \n";
//TRAVERSING WAS/IS A BAD IDEA.............................
    while ( Current != NULL )
    {
     if ( Current->data_ == node->data_ )
     {
      //If Current isn't the head of the list, set prev to next
      if ( Current != first_ )
      {
       Current->prev_    = first_; //statement that follows crashes if this is not assigned.
       Current->prev_->next_ = Current->next_;
      }
      else
      {
       first_ = Current->next_;
       if ( first_ != NULL )
       first_->prev_ = NULL;
      }

      //If Current isn't the tail of the list, set next to prev
      if ( Current->next_ != NULL )
       Current->next_ = Current->prev_;

      else if ( Current->prev_ != NULL )
      Current->prev_->next_ = NULL;

       listLen_--;
       delete Current;
       Current = NULL;
     }
     else
     {
      Current->prev_ = Current;
      Current = Current->next_;
     }
    }
    return;
}

Code for PrintAllNodes in main.cpp:

void PrintAllNodes( LinkedList *LinkedObject, long length = 0 )
{
    const char *Names = NULL; 
    length = LinkedObject->GetListLength();
    Node *GetNode = LinkedObject->GetFirstNode();

    for ( signed short x = 0; x < length; x++ )
    {
     Names = static_cast< NameObject* >( GetNode->data_ )->GetName();
     cout << Names << endl;
     GetNode = GetNode->next_; // traversing
    }
    return;
}

Answer 1

This is your problem:

Current->prev_  = first_;

What you're doing is disconnecting all nodes before current and connecting the first to the last! (the seventh in your case)

What you should do there is only:

Current->prev_->next_ = Current->next_;
Current->next_->prev_ = Current->prev_; //I think you forgot this
delete Current;
Current = NULL;

If without the

Current->prev_  = first_;

you get a crash, that's because your Current->prev_ isn't assigned well. But assigning it to first_ is not the solution. You should check your other methods (maybe the AddNode) to see why your Current->prev_ is bad.