preface

书名:C语言科学与艺术,以前交钱下载的

of that approach is reflected in the following two features that set
this book apart from other introductory texts:

  1.  Libraries and modular development -- essential concepts in
      modern programming -- are covered in considerable detail early
      in the presentation. Part II focuses entirely on the topics of
      libraries, interfaces, abstractions, and modular development.
      Students learn how to use these techniques effectively before
      they learn about arrays.

  2.  The text demonstrates the power of libraries by using them.
      It is one thing to tell students that libraries make it
      possible to hide complexity.  It is quite another to
      demonstrate that concept.  This text introduces several new
      libraries that hide details from the students until they are
      ready to assimilate them.  The libraries give students th e
      power to write useful programs that they could not develop on
      their own.  Later chapters reveal the implementation of those
      libraries, thereby allowing students to appreciate the power
      of abstraction.

In 1992, I attempted to teach the introductory course using only the
ANSI libraries.  The results were not encouraging.  Each new topic
required that the student understand so much about the rest of C that
there was no effective way to present the material.  For example,
students had to understand the mechanics of arrays, pointers, and
allocation before they could use string data in any interesting way,
even though string manipulation is simpler conceptually.  My best
students managed to understand what was going on by the end of the
quarter.  Most, however, did not.  Since we introduced the library-based
approach in 1993, students have assimilated the material more easily and
learned much more about computer science.

The library interfaces and associated implementations used in this text
are reprinted in Appendix B, which also gives instructions for obtaining
the source code electronically through anonymous FTP (File Transfer
Protocol).

THE ORDER OF PRESENTATION

This book presents topics in the same order as Stanford's introductory
course, except for the material in Chapter 17, which we cover in the
second course.  Depending on your audience and the goals of your course,
you may want to vary the order of presentation.  The following notes
provide an overview of the chapters and indicate some of the more
important dependencies.

Chapter 1 traces the history of computing and describes the programming
process.  The chapter requires no programming per se but provides the
contextual background for the rest of the text.

I have designed Chapters 2 and 3 for students with little or no
background in programming.  These chapters are conceptual in their
approach and focus on problem solving rather than on the details of the
C language.  When new students are faced with detailed rules of syntax
and structure, they concentrate on learning the rules instead of the
underlying concepts, which are vastly more important at this stage.  If
your students already know some programming, you could move much more
quickly through this material.

Chapters 2 and 3 are informal in their approach and concentrate on
developing the student's problem-solving skills.  Along the way, they
introduce several basic statement forms and control structures, but only
as idioms to accomplish a specific task.  Chapter 4 adds formal
structure to this topic by describing each statement form in turn,
detailing its syntax and semantics.  The chapter also includes an
extensive discussion of Boolean data.

Chapter 5 introduces functions and procedures.  It begins with simple
examples of functions and then continues with increasingly sophisticated
examples.  The mechanics of parameter passing are discussed in a
separate section that includes many diagrams to help students follow the
flow of data from one function to another.  The chapter ends with a
significant programming example that illustrates the concept of stepwise
refinement.

The algorithmic concepts presented in Chapter 6 are fundamental to
computer science but may not be required for all students.  If your
audience consists of engineers or potential computer science majors, the
material will prove extremely valuable.  For less technical audiences,
however, you can eliminate much of this material without disturbing the
flow of the presentation.

I have found that integrating graphics in the introductory course is a
great way to increase student interest in the material.  Chapter 7
exists for that reason.  At this stage, students have learned the
mechanics of functions but have no burning need to write them.  Letting
students draw complex pictures on the screen gives them that incentive.
The graphics library is implemented for several of the major programming
environments and can therefore be used in most institutions.

Chapter 8 has two themes, which are in some sense separable.  The first
part of the chapter discusses design criteria for interfaces and is
essential for anyone who needs to understand how modern programming
works.  The second part of the chapter applies those principles to build
a random number library.  The random.h interface itself is less
important than the general principles, although use of the random number
library is required for many exercises throughout the text.

Chapter 9 introduces strings as an abstract type and represents, to a
certain extent, the cornerstone of the library-based approach.  By using
a dynamic string library, students can easily write programs that
perform sophisticated string manipulation, even though they do not yet
understand the underlying representation, which is covered in Chapter
14.  Introducing strings at this point in the presentation enables
students to write much more exciting programs that they could otherwise.

On a first reading, it is easy to miss the purpose of Chapter 10, which
appears to be an extension of the discussion of strings begun in Chapter
9.  The fundamental value of Chapter 10 does not lie in the Pig Latin
program, which is more fun than it is practical.  The entire reason for
the example is that it provides the motivation to build the scanner
interface used to separate words on the input line.  The scanner module
proves its usefulness over and over again, not only in the first course,
but in subsequent courses as well.  It is the most practical tool
students create in the course and therefore serves as a compelling
example of the value of modularity.

Chapters 11 through 16 introduce the fundamental compound structures --
arrays, records, pointers, and files -- in an order that has worked well
in practice.  Because the base language is C, it is important to present
pointers as soon as possible after introducing arrays so that you can
emphasize the connections between them.  Moreover, having established
these concepts, it is then possible in Chapter 14 to consider string
data more closely, thereby revealing the underlying representation that
was concealed by the abstract definition.  Chapter 16 integrates the
fundamental data structures with the construction of a data-driven
teaching machine, which is the most sophisticated example of programming
presented in the text.

Chapter 17 includes three important topics that often appear in the
first programming course: recursion, abstract data types, and analysis
of algorithms.  At Stanford, which is on the quarter system, we teach
all these topics in the second course.  If you decide to teach recursion
in the first course, I strongly recommend that you do so early enough to
allow students time to assimilate the material.  One possibility is to
discuss recursive functions immediately after Chapter 5 and recursive
algorithms after Chapter 6.  Another approach is to cover recursion and
analysis of algorithms together at the end of Chapter 12.

INSTRUCTOR'S MANUAL

The Instructor's Manual contains supplemental materials including a
course syllabus, suggestions for lecture design, sample assignments and
examinations, and solutions to all programming exercises.  In addition
to the printed manual, instructor's who adopt this text can retrieve
electronic copies of solution sets and related materials.  For details
on obtaining solutions, please contact your local Addison-Wesley
representative.  All other supplemental material is available on-line.
For explicit instructions see Appendix B.