File Structures: An Object-Oriented Approach with C++
The first and second editions of File Structures by Michael Folk and Bill Zoellick established a standard for teaching and learning about file structures. The authors helped many students and computing professionals gain familiarity with the tools used to organize files.This book extends the presentation of file structure design that has been so successful for twelve years with an object-oriented approach to implementing file structures using C++. It demonstrates how the object-oriented approach can be successfully applied to complex implementation problems. It is intended for students in computing classes who have had at least one programming course and for computing professionals who want to improve their skills in using files.This book shows you how to design and implement efficient file structures that are easy for application programmers to use. All you need is a compiler for C++ or other object-oriented programming language and an operating system. This book provides the conceptual tools that enable you to think through alternative file structure designs that apply to the task at hand. It also develops the programming skills necessary to produce quality implementations.The coverage of the C++ language in this book is suitable for readers with a basic knowledge of the language. Readers who have a working familiarity with C++ should have no problem understanding the programming examples. Those who have not programmed in C++ will benefit from access to an introductory textbook.The first programming examples in the book use very simple C++ classes to develop implementations of fundamental file structure tools. One by one, advanced features of C++ appear in the context of implementations of more complex file structure tools. Each feature is fully explained when it is introduced. Readers gain familiarity with inheritance, overloading, virtual methods, and templates and see examples of why these features are so useful to object-oriented programming.  Organization of the BookThe first six chapters of this book give you the tools to design and implement simple file structures from the ground up: simple I/O, methods for transferring objects between memory and files, sequential and direct access, and the characteristics of secondary storage. The last six chapters build on this foundation and introduce you to the most important high-level file structure tools, including indexing, cosequential processing, B-trees, B+ trees, hashing, and extendible hashing.The book includes extensive discussion of the object-oriented approach to representing information and algorithms and the features of C++ that support this approach. Each of the topics in the text is accompanied by object-oriented representations. The full C++ class definitions and code are included as appendices and are available on the Internet. This code has been developed and tested using Microsoft Visual C++ and the Gnu C++ compilers on a variety of operating systems including Windows 95, Windows NT, Linux, Sun Solaris, and IBM AIX.   Object-Oriented File StructuresThere are two reasons we have added the strong object-oriented programming component to this book. First, it allows us to be more specific, and more helpful, in illustrating the tools of file structure design. For each tool, we give very specific algorithms and explain the options that are available to implementers. We are also able to build full implementations of complex file structure tools that are suitable for solving file design problems. By the time we get to B-tree indexing, for instance, we are able to use previous tools for defining object types, moving data between memory and files, and simple indexing. This makes it possible for the B-tree classes to have simple implementations and for the book to explain the features of B-trees as enhancements of previous tools.The second purpose of the programming component of the book is to illustrate the proper use of object-oriented methods. Students are often exposed to object-oriented techniques through simple examples. However, it is only in complex systems that the advantages of object-oriented techniques become clear. In this book, we have taken advantage of the orderly presentation of file structure tools to build a complex software system as a sequence of relatively simple design and implementation steps. Through this approach, students get specific examples of the advantages of object-oriented methods and are able to improve their own programming skills.  A Progressive Presentation of C++We cover the principles of design and implementation in a progressive fashion. Simple concepts come first and form the foundation for more complex concepts. Simple classes are designed and implemented in the early chapters, then are used extensively for the implementation topics of the later chapters. The most complex file structure tools have simple implementations because they extend the solid foundation of the early chapters.We also present the features of C++ and the techniques of object-oriented programming in a progressive fashion. The use of C++ begins with the simplest class definitions. Next comes the use of stream classes for input and output. Further examples introduce inheritance, then virtual functions, and finally templates.Each new feature is introduced and explained in the context of a useful file structure application. Readers see how to apply object-oriented techniques to programming problems and learn firsthand how object-oriented techniques can make complex programming tasks simpler.  Exercises and Programming ProblemsThe book includes a wealth of new analytical and programming exercises. The programming exercises include extensions and enhancements to the file structure tools and the application of those tools. The tools in the book are working software, but some operations have been left as programming problems. The deletion of records from files, for instance, is discussed in the text but not implemented. Specific programming problems fill in the gaps in the implementations and investigate some of the alternatives that are presented in the text.An application of information processing is included as a series of programming projects in the exercise sets of appropriate chapters. This application begins in Chapter 1 with the representation of students and courses registrations as objects of C++ classes. In Chapter 2, the project asks for simple input and output of these objects. Later projects include implementing files of objects (Chapter 4), indexes to files (Chapter 7), grade reports and transcripts (Chapter 8), B-tree indexes (Chapter 9), and hashed indexes (Chapter 12).   Using the Book as a College TextThe first two editions of File Structures have been used extensively as a text in many colleges and universities. Because the book is quite readable, students typically are expected to read the entire book over the course of a semester. The text covers the basics; class lectures can expand and supplement the material. The professor is free to explore more complex topics and applications, relying on the text to supply the fundamentals.A word of caution: It is easy to spend too much time on the low-level issues presented in the first seven chapters. Move quickly through this material. The relatively large number of pages devoted to these matters is not a reflection of the percentage of the course that should be spent on them. The intent is to provide thorough coverage in the text so the instructor can assign these chapters as background reading, saving precious lecture time for more important topics.It is important to get students involved in the development of file processing software early in the course. Instructors may choose some combination of file tool implementation problems from the programming exercises and applications of the tools from the programming projects. Each of the programming problems and projects included in the exercises is intended to be of short duration with specific deliverables. Students can be assigned programming problems of one to three weeks in duration. It is typical for one assignment to depend on previous assignments. By conducting a sequence of related software developments, the students finish the semester with extensive experience in object-oriented software development.  A Book for Computing ProfessionalsWe wrote and revised this book with our professional colleagues in mind. The style is conversational; the intent is to provide a book that you can read over a number of evenings, coming away with a good sense of how to approach file structure design problems. Some computing professionals may choose to skip the extensive programming examples and concentrate on the conceptual tools of file structure design. Others may want to use the C++ class definitions and code as the basis for their own implementations of file structure tools.If you are already familiar with basic file structure design concepts and programming in C++, skim through the first six chapters and begin reading about indexing in Chapter 7. Subsequent chapters introduce you to cosequential processing, B-trees, B+ trees, hashing, and extendible hashing. These are key tools for any practicing programmer who is building file structures. We have tried to present them in a way that is both thorough and readable.The object-oriented C++ design and the implementation included throughout the book provide an extensive tour of the capabilities of the language and thorough examples of object-oriented design. If you need to build and access file structures similar to the ones in the text, you can use the C++ code as class libraries that you can adapt to your needs. A careful reading of the design and implementation examples can be helpful in enhancing your skills with object-oriented tools. All of the code included in the book is available on the Internet.If you are not already a serious Unix user, the Unix material in the first eight chapters will give you a feel for why Unix is a powerful environment in which to work with files.   Supplementary MaterialsThe following supplementary materials are available to assist instructors and students.An Instructors' Guide including answers to exercises will be available. Instructors should contact their Addison-Wesley local sales representative for information on the Guide's availability. Programming examples and code will also be available via anonymous ftp at ftp.aw/cseng/authors/riccardi.  AcknowledgementsIt is a pleasure to acknowledge the outstanding work of Mike Folk and Bill Zoellick. As one who taught from the original work, I am pleased to add my contribution to its evolution.There are many people I would like to thank for help in preparing this revision of File Structures. The staff of the Computer and Engineering Publishing Group of Addison-Wesley was extremely helpful. Editor Susan Hartman approached me to revise this excellent book and add a C++ programming component. She was responsible for getting all of the complex pieces put together. Katherine Harutunian, associate editor, was helpful and good-humored during the long and stressful process. The production staff of Patricia Unubun, Brooke Albright, and Amy Willcutt worked with me and were able to get the book finished on time.I am particularly appreciative of the reviewers: H. K. Dai, Ed Boyno, Mary Ann Robbert, Barbara L. Laguna, Kenneth Cooper Jr., and Mathew Palakal. Their comments and helpful suggestions showed me many ways to improve the book, especially in the presentation of the programming material.My greatest debt is to my wife, Ann, and my daughters, Mary, Christina, and, Elizabeth for giving me the time to work on this project. It was their support that allowed me to carry this project to completion.Greg RiccardiTallahassee, Floridariccardi@cs.fsu0201874016P04062001