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Doubly linked List promblems.

gladi (68)
Hi Everyone,
Kindly, I need some help with this code. This question is about I have to convert single linked list to doubly linked list. so, I tried to solve this but I have some errors.

This is a single linked list before converting

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  template< typename NODETYPE >
void List< NODETYPE >::insertAtFront( const NODETYPE &value )
{
   ListNode< NODETYPE > *newPtr = getNewNode( value ); // new node
   

   if ( isEmpty() ) // List is empty
	   {
		  firstPtr = lastPtr = newPtr;
	   }
	   // new list has only one node
   else // List is not empty
	   {
		  newPtr->nextPtr = firstPtr; // point new node to previous 1st node
		  firstPtr = newPtr; // aim firstPtr at new node
	   } // end else
} // end function insertAtFront


This is after I change in the first condition.

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template< typename NODETYPE >
void List< NODETYPE >::insertAtFront( const NODETYPE &value )
{
   ListNode< NODETYPE > *newPtr = getNewNode( value ); // new node
   ListNode< NODETYPE > *temp;

   if ( isEmpty() ) // List is empty
	   {
		  newPtr = new Node;
		  firstPtr = newPtr;
		  lastPtr = newPtr;
		  newPtr ->nextPtr = NULL;
		  newPtr ->prevPtr = NULL;
		  newPtr ->data = value;
	   }
	   // new list has only one node
   else // List is not empty
	   {
		  newPtr->nextPtr = firstPtr; // point new node to previous 1st node
		  firstPtr = newPtr; // aim firstPtr at new node
	   } // end else
} // end function insertAtFront

I have an error in Line 9 the
syntax error : identifier 'Node'
gladi (68)
Please anyone can help :(
vlad from moscow (6539)
There is no any sense in the statement

newPtr = new Node;

You already initialized newPtr in the previous statement

ListNode< NODETYPE > *newPtr = getNewNode( value ); // new node

Also you should check whether function getNewNode( value ); has already within its body statements similar to

newPtr ->nextPtr = NULL;
newPtr ->prevPtr = NULL;




Last edited on
naraku9333 (2163)
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ListNode< NODETYPE > *newPtr = getNewNode( value ); // new node
   ...
	newPtr = new Node;
Memory leak?

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else // List is not empty
       {
		  newPtr->nextPtr = firstPtr; // point new node to previous 1st node
                  firstPtr->prevPtr = newPtr;
		  firstPtr = newPtr; // aim firstPtr at new node
	   } // end else


Edit: Didn't see Vlad's post.
Last edited on
gladi (68)
ohh.. it is obvious.
sorry about that I didn't notice this. I delete that line and it works.

Thank you so much
vlad from moscow
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