コード例 #1
0
 public void RemoveFirst()
 {
     if (Count != 0)
     {
         _head = _head.Next;           // 2nd item becomes new head.
         Count--;                      // Count decreases.
         if (Count == 0)
         {
             _tail = null;              // If there are no items, tail is now null too.
         }
         else
         {
             _head.Previous = null;     // new head's Previous should point to null
         }
         // I wondered why this was in the if/else rather than simply being above Count--
         // but I think it's because this operation is not necessary if the item had been
         // a singleton and spares us one command in that case.
     }
 }
コード例 #2
0
        public void RemoveLast()
        {
            if (Count != 0)
            {
                _tail = _tail.Previous;
                Count--;
                if (Count == 0)
                {
                    _head = null;
                }
                else
                {
                    _tail.Next = null;
                }

                // I don't know why, but the book broke pattern here and created a
                // if (Count == 1) case where _head and _tail are set to null.
                // but this is accounted for with the above code, keeping the same pattern
                // as our RemoveFirst method.  I.e., if there is one item in the list,
                // _tail.Previous is null so _tail becomes null.  When you do Count--
                // Count becomes 0, then _head is set to null, resulting in null/null.
            }
        }
コード例 #3
0
 public void Clear()
 {
     _head = null;
     _tail = null;
     Count = 0;
 }