#include <iostream.h>
#include <ctype.h>     // Provides toupper
#include <stdlib.h>    // Provides EXIT_SUCCESS and size_t
#include <assert.h>
class List
{  public:
      enum { CAPACITY = 3 };  // or, static const size_t CAPACITY = 30;
      typedef double Item;
      List( ) { used = 0; }
      void start( ) { current_index = 0; }
      void advance( ) { current_index++; }
      void insert(const Item& entry);
      void attach(const Item& entry);
      void remove_current( );
      size_t size( ) const { return used; }
      bool is_item( ) const { return (current_index < used)? true:false; }
      size_t index ( ) const { return current_index; }
      Item current( ) const { return data[current_index]; }
   private:
      Item data[CAPACITY];
      size_t used;
      size_t current_index;
};

void List::remove_current( )
{  assert(is_item());
   for(int i = current_index + 1; i < used; i++)
      data[i-1] = data[i];
   used--;
}

void List::insert(const Item& entry)
{  size_t i;
   assert(size() < CAPACITY);
   if(!is_item())
      current_index = 0;
   for(i = used; i > current_index; i--)
      data[i] = data[i-1];
   data[current_index] = entry;
   used++;
}

void List::attach(const Item& entry)
{  size_t i;
   assert(size() < CAPACITY);
   if(!is_item())
      current_index = used;
   else
   {  for(i = used; i > current_index + 1; i--)
         data[i] = data[i-1];
      current_index += 1;
   }
   data[current_index] = entry;
   used++;
}

void print_menu( )
{   cout << "\nThe following choices are available: " << endl;
    cout << " !   Activate the start( ) function" << endl;
    cout << " +   Activate the advance( ) function" << endl;
    cout << " ?   Print the result from the is_item( ) function" << endl;
    cout << " C   Print the result from the current( ) function" << endl;
    cout << " P   Print a copy of the entire List (also index and used)" << endl;
    cout << " I   Insert a new number with the insert(...) function" << endl;
    cout << " A   Attach a new number with the attach(...) function" << endl;
    cout << " R   Activate the remove_current( ) function" << endl;
    cout << " Q   Quit this test program" << endl;
}

char get_user_command( )
{   char command;
    cout << "Enter choice: ";
    cin >> command; // Input of characters skips blanks and newline character
    return command;
}

void show_list(List display) // call by value!
{   cout << "Current Index = " << display.index() <<  "    "
         << "Used Size = " << display.size() << endl;
    cout << "( ";
    for (display.start( ); display.is_item( ); display.advance( ))
        cout << display.current( ) << " ";
    cout << ")";
}

double get_number( )
{   double result;
    cout << "Please enter a real number for the List: ";
    cin  >> result;
    cout << result << " has been read." << endl;
    return result;
}

void main( )
{   List test;    // A List that we'll perform tests on
    char choice;  // A command character entered by the user
    cout << "I have initialized an empty List of real numbers." << endl;
    do
    {   print_menu( );
        choice = (char)toupper(get_user_command( ));
        switch (choice)
        {   case '!': test.start(); break;
            case '+': test.advance( ); break;
            case '?': if (test.is_item( ))
                          cout << "There is an item." << endl;
                      else
                          cout << "There is no current item." << endl;
                      break;
            case 'C': if (test.is_item( ))
                         cout << "Current item is: " << test.current( ) << endl;
                      else
                         cout << "There is no current item." << endl;
                      break;
            case 'P': show_list(test); break;
            case 'I': test.insert(get_number( )); break;
            case 'A': test.attach(get_number( )); break;
            case 'R': test.remove_current( );
                      cout << "The current item has been removed" << endl;
                      break;
            case 'Q': cout << "Ridicule is the best test of truth." << endl;
                      break;
            default:  cout << choice << " is invalid. Sorry." << endl;
        }
    }
    while ((choice != 'Q'));
}