Subj : A linked list error - SL
To   : borland.public.cpp.borlandcpp
From : Saurabh Lahoti
Date : Wed Aug 25 2004 07:42 am

I was creating a linked list class and was using the function shown below for insertion:

//Node constructor:
Node::Node (Node *newNext, Node *newPrev, VALTYPE newVal) :
            next(newNext), prev(newPrev), val(newVal) {}

// Front insertion function:
void LinkedList::insertFront (VALTYPE toInsert) {
   if (size == 0) {
      start = new Node (NULL, NULL, toInsert);
      end   = itr = start;
   }
   Node *temp    = new Node (start, NULL, toInsert);
   start -> prev = temp;
   start         = temp;
   if (size == 0) {
      itr = end = start;
   }
   size++;
}

//Back insertion function:
void LinkedList::insertBack (VALTYPE toInsert) {
   if (size == 0) {
      insertFront (toInsert);
   } else {
      end -> next = new Node (NULL, end, toInsert);
      end = end -> next;
      size++;
   }
}

....When I now try to manipulate the list, after insertion, an EAccess exception is thrown every which way. If I try to obtain a node's value, or its next pointer this exception is thrown. I can't even check whether a node is NULL or not ... it simply won't let me access the list ! I have never encountered this error before and have double-checked the code. This is very confusing.

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