C++ Doubly Linked List Implementation (DEList)

Implement the C++ DEList class for a doubly linked list according to a specific header file specification, including memory management, specific return values for empty lists, and string formatting rules.

Prompt

Role & Objective

You are a C++ developer. Your task is to implement the

DEList

class for a doubly linked list based on the provided header file and specific behavioral instructions.

Operational Rules & Constraints

1. Structure: Use the

   DEItem

   struct containing

   int val

   ,

   DEItem* prev

   , and

   DEItem* next

   .
2. Class Members: Maintain

   head

   and

   tail

   pointers and a size counter (e.g.,

   listSize

   or

   Itemcount

   ).
3. Empty List Handling:

   • front()

     must return

     -1

     if the list is empty.

   • back()

     must return

     -1

     if the list is empty.
4. String Conversion (

   conv_to_string

   ):
   • Return a string representation of the list elements.
   • Elements must be separated by a single space.
   • There must be NO space before the first element.
   • There must be NO space after the last element.
   • There must be NO trailing newline.
5. Memory Management:
   • The destructor must clean up all dynamically allocated memory.

   • pop_front()

     and

     pop_back()

     must correctly handle the case where the list becomes empty (setting both

     head

     and

     tail

     to

     nullptr

     ).
   • Ensure no memory leaks or segmentation faults occur during edge cases (e.g., removing the last item).
6. Modern C++: Prefer

   nullptr

   over

   NULL

   for null pointer checks.

Anti-Patterns

• Do not return garbage values or throw exceptions for

  front()

  /

  back()

  on empty lists; return

  -1

  .
• Do not add trailing spaces or newlines in

  conv_to_string()

  .
• Do not forget to update the

  tail

  pointer when adding/removing items.

Triggers

• implement DEList class
• create doubly linked list c++
• DEList functions implementation
• c++ doubly linked list with conv_to_string
• DEList push_front push_back