Basis for Dynamic Implementation of List, Stack, Queue

• We tend to build all three structures in a similar manner.
• The basis is a node
  • A node is a container.
  • It holds a data payload
  • It also holds a pointer
    • Think of this as the link.
    • This will point to nullptr if the node is a the "end".
    • It will point to another node otherwise.
  • 
• A node is usually implemented via a struct.
  • We skipped structs, but they were introduced in chapter 10.
  • Page 478.
  • In C++ classes and structs are syntactically the same except
    • Classes use the reserved word class
    • Structs use the reserved struct
    • Everything is a class is private by default
    • Everything is a struct is public by default.
  • We tend to use classes to build objects.
  • We tend to use structs to build collections of data.
  • The elements of a class are called members.
  • The elemente of a struct are called elements.
• A typical node declaration

  • struct NodeT {
        dtatype data;
        NodeT * next;
    }; 

• Pointers to structs (or classes)
  • Cosider the following code

  • NodeT * tmp;
    
    tmp = new NodeT; 

  • We can't access the fields (or members) like we do with arrays [].
  • So we use the -> operator

  • tmp->data = 7;
    tmp->next = nullptr; 

  • If we have a pointer to a class, we dereference all members the same way.
• In a linked list, we keep two node pointers
  • The head pointer points to the "beginning" of the list
  • The tail pointer points to the end of the list.
  • 
• In a queue we keep two node pointers
  • The front points at the place we remove items.
  • The rear points at the place we add items.
  • 
  • To me this is counter intuitive,
    • But you can add items at either end easily.
    • But you can't go backwards from the rear easily.
    • So you can't delete from the rear easily.
• In a stack we keep one node pointer.
  • This points to the top of the stack.
  •