// Linked List 0 - Using "struct"
#include <stdlib.h> // Provides size_t
#include <assert.h>
#include <iostream.h>

struct Node
{    typedef double Item;
     Item data;
     Node *link;
};

size_t list_length(Node* head_ptr)
{   Node *cursor;
    size_t answer = 0;
    for (cursor = head_ptr; cursor != NULL; cursor = cursor->link)
        answer++;
    return answer;
}

void list_display(Node* head_ptr)
{   Node *cursor;
    cout << "( ";
    for (cursor = head_ptr; cursor != NULL; cursor = cursor->link)
       cout << cursor->data << " ";
    cout << "), " << "Size = " << list_length(head_ptr) << endl << endl;
}

void list_head_insert(Node*& head_ptr, const Node::Item& entry)
{   Node *insert_ptr = new Node;
    insert_ptr->data = entry;
    insert_ptr->link = head_ptr;
    head_ptr = insert_ptr;
}

void list_append(Node*& head_ptr, const Node::Item& entry) // insert to the rear
{   Node *cursor, *append_ptr;
    for (cursor = head_ptr; cursor->link != NULL; cursor = cursor->link);
    append_ptr = new Node;
    append_ptr->data = entry;
    append_ptr->link = NULL;
    cursor->link = append_ptr;
}

void main()
{  Node *head = NULL;  // NULL from stdlib.h
   Node::Item in;
   cout << "Enter numbers to create a linked list (-1 at the end): ";
   cin >> in;
   while (in > 0.0)
   {  list_head_insert(head, in);
      cin >> in;
   }

   list_display(head);
   cout << "Enter a number to be inserted at the head of the linked list: ";
   cin >> in;
   list_head_insert(head, in);
   list_display(head);
   cout << "Enter a number to be appended to the rear of the linked list: ";
   cin >> in;
   list_append(head, in);
   list_display(head);
}