////   This file contains the C++ code from Program 7.11 of//   "Data Structures and Algorithms//    with Object-Oriented Design Patterns in C++"//   by Bruno R. Preiss.////   Copyright (c) 1998 by Bruno R. Preiss, P.Eng.  All rights reserved.////   http://www.pads.uwaterloo.ca/Bruno.Preiss/books/opus4/programs/pgm07_11.cpp//ListAsLinkedList::ListAsLinkedList () :    linkedList ()    {}void ListAsLinkedList::Insert (Object& object){    linkedList.Append (&object);    ++count;}Object& ListAsLinkedList::operator [] (unsigned int offset) const{    if (offset >= count)	throw out_of_range ("invalid offset");    unsigned int i = 0;    ListElement<Object*> const* ptr =	linkedList.Head ();    while (i < offset && ptr != 0)    {	ptr = ptr->Next ();	++i;    }    if (ptr == 0)	throw logic_error ("should never happen");    return *ptr->Datum ();}