Table Of ContentPascal
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SECOND EDmON
Douglas W. Nance
CENTRAL MICHIGAN UNIVERSITY
WEST PUBUSHING COMPANY
ST. PAUL NEW YORK LOS ANGELES SANFRANQSCO
To Helen
Copyeditor and Indexer: Janet Hunter
Interior design: Paula Schlosser and Lucy Leslak
Illustrations: Christine Dettner and Rolin Graphics
Composition: Carlisle Communications
COPYRIGHT ©1984 By WEST PUBLISHING COMPANY
COPYRIGHT ©1989 By WEST PUBLISHING COMPANY
50 W. Kellogg Boulevard
P.O. Box 64526
St. Paul, MN 55164-1003
All rights reserved
Printed in the United States of America
96 95 94 93 92 91 90 89 8 7 6 5 4 3 2 1 0
Library of Congress Cataloging-in-Publication Data
Nance, Douglas W.
Pascal: understanding programming and problem solving / Douglas
W. Nance.—2nd ed.
p. cm.
Includes index.
ISBN 0-314-43051-2
1. Pascal (Computer program language) I. Title.
QA76.73.P2N35 1989
005.13'3—dcl9 88-29307
CIP
X
Contents
n
1 Computer Science, Computer
CHAPTER
Architecture, and Computer Languages
Computer Science: A Preview 1
1.1
Computer Architecture 4
1.2
A Note of Interest: Microprocessors 8
Computer Languages 9
1.3
A Note of Interest: Why Learn Pascal? 12
Summary 13
CHAPTER 2 ■Writing Your First Programs
14
Program Development—Top-Down Design 15
2.1
A Note of Interest: Software Engineering 21
2.2 Writing Programs 22
A Note of Interest: Blaise Pascal 32
Data Types and Output 33
2.3
Style Tip • 37
Style Tip 42
Summary 45
Programming Problems 46
3 "Arithmetic, Variables, Input, Constants,
CHAPTER
and Standard Functions 47
3.1 Arithmetic in Pascal 47
3.2 Using Variables 52
3.3 Input 59
vi Contents
3.4 Using Constants 68
A Note of Interest: Defined Constants and Space
Shuttle Computing 69
3.5 Standard Functions 71
A Note of Interest: Herman Hollerith 74
Style Tip 78
Summary 78
Programming Problems 80
n
CHAPTER 4 Designing and Writing Complete
Programs 82
4.1 Writing Code 82
A Note of Interest: Documentation Employment 91
4.2 Procedures for Output 96
Style Tip 103
4.3 Beginners' Errors 111
4.4 Mciking a Program Run 120
Style Tip 121
A Note of Interest: Debugging 123
4.5 Writing a Complete Pascal Program 128
A Note of Interest: Debugging or Sleuthing? 130
Summary 136
A Note of Interest: Debugging or Sleuthing: Answers 137
Programming Problems 138
n
CHAPTER 5 Conditional Statements 145
5.1 Boolean Expressions 145
A Note of Interest: George Boole 153
5.2 IF ... THEN Statements 156
5.3 IF ... THEN ... ELSE Statements 164
5.4 Nested IF Statements 169
Style Tip 173
5.5 CASE Statements 180
Style Tip 182
A Note of Interest: "Cross-Over" Scholars 185
5.6 Assertions (Optional) 188
Focus on Programming 189
Running and Debugging Tips 194
Summary 195
Programming Problems 196
n
CHAPTER 6 Looping Statements 203
6.1 Fixed Repetition Loops 203
Style Tip 211
A Note of Interest: Ada Augusta Byron 212
Contents Vll
6.2 Pretest Loops 214
A Note of Interest: Debugging Space Flight Programs 222
6.3 Posttest Loops 228
A Note of Interest: Charles Babbage 231
6.4 Comparison of Loops 235
6.5 Nested Loops 239
Style Tip 241
6.6 Loops with Conditionals 247
A Note of Interest: A Digital Matter of Life and Death 249
Focus on Programming 253
Running and Debugging Tips 258
Summary 258
Programming Problems 261
chapter 7"Functions and Procedures ^
7.1 Program Design 264
A Note of Interest: Structured Programming 265
7.2 Functions 265
7.3 Procedures 273
A Note of Interest: Ada 283
7.4 Scope of Identifiers 287
7.5 Using Subprograms 297
A Note of Interest: Niklaus Wirth: Pascal to Modula-2 300
7.6 Forward Reference and Nesting 307
Style Tip 308
Focus on Programming 314
Running and Debugging Tips 319
Summary 319
Programming Problems 322
CHAPTER 8"Text Files and User-Defined Data Types 324
8.1 Text Files 324
8.2 TYPE Definitions in Pascal 335
A Note of Interest: The Software System Life Cycle 339
8.3 Subrange as a Data Type 341
Style Tip 344
8.4 Operations on Ordinal Data Types 346
A Note of Interest: There's a Virus in My Software! 348
Focus on Programming 351
Running and Debugging Tips 355
Summary 355
Programming Problems 357
Vlll Contents
n
CHAPTER 9 One-Dimensional Arrays 360
9.1 Basic Ideas and Notation 360
Style Tip 364
A Note of Interest: Monolithic Idea: Invention of the Integrated
Circuit 368
9.2 Using Arrays 370
Style Tip 376
9.3 Selection Sort 379
A Note of Interest: Transition to a Computer System 380
9.4 Arrays and Subprograms 385
9.5 Packed Arrays 393
A Note of Interest: Data Abstraction 398
9.6 Searching Algorithms 403
Focus on Programming 408
Running and Debugging Tips 414
Summary 415
Programming Problems 417
CHAPTER 10"A rrays of More Than One Dimension 422
10.1 Two-Dimensional Arrays 422
Style Tip 424
A Note of Interest: Telesecurity 433
10.2 Arrays of String Variables 436
10.3 Parallel Arrays (Optional) 440
Style Tip 440
A Note of Interest: Software Destruction 442
10.4 Higher-Dimensional Arrays 447
A Note of Interest: Computer Security 450
Focus on Programming 452
Running and Debugging Tips 460
Summary 460
Programming Problems 462
CHAPTER 11 ■Records 469
11.1 Record Definitions 469
Style Tip 473
A Note of Interest: Computer Industry Growth 473
11.2 Using Records 478
A Note of Interest: Using Key Fields in Records 486
11.3 Data Structures with Records 490
A Note of Interest: Neural Nets Catch the ABCs of DNA 493
11.4 Record Variants 501
Focus on Programming 506
Running and Debugging Tips 512
Summary 512
Programming Problems 514
Contents IX
CHAPTER 12 n Files 518
12.1 File Definition 518
12.2 Working with Files 521
A Note of Interest: Relational Databases 528
12.3 Files with Structured Components 532
A Note of Interest: Backup and Recovery 537
Focus on Progranmiing 539
Running and Debugging Tips 547
Summary 548
Programming Problems 550
CHAPTER 13■Recursion, Sorting, and Merging 554
13.1 Recursion 554
13.2 Sorting Algorithms 564
A Note of Interest: Sex Differences in the Association between
Secondary School Students' Attitudes toward Mathematics and
toward Computers 566
13.3 Merging Algorithms 574
Running and Debugging Tips 578
Summary 578
Suggestions For Further Reading 579
Programming Problems 579
CHAPTER 14 ■ Sets 581
14.1 Declarations and Terms 581
A Note of Interest: Developing Educational Software 583
14.2 Set Operations and Relational Operators 585
14.3 Using Sets 588
Style Tip 589
A Note of Interest: Time Is Cure for Computerphobia 592
Focus on Programming 593
Running and Debugging Tips 597
Summary 598
Programming Problems 599
CHAPTER 15■Dynamic Variables and Data Structures 603
15.1 Pointer Variables 604
Style Tip 606
15.2 Linked Lists 610
Style Tip 610
15.3 Working with Linked Lists 617
Style Tip 617
A Note of Interest: Using Pointers 627
X Contents
15.4 Other Dynamic Data Structures 630
Running and Debugging Tips 641
Summary 642
Suggestions for Further Reading 645
Programming Problems 645.
'Appendixes A.l
Appendix 1 Reserved Words A.2
Appendix 2 Standard Identifiers A.3
Appendix 3 Syntax Diagrams A.5
Appendix 4 Character Sets A.16
Appendix 5 Compiler Error Messages A.1 8
Appendix 6 Turbo Pascal Notes A.21
Appendix 7 GOTO Statements A.27
Glossary G.l
Answers to Selected Exercises AN.i
Index I.i
Preface
Those who teach entry-level courses in computer science are fa
miliar with the problems that beginning students encounter. Ini
tially, students can get so involved in learning a language that they may
fail to grasp the significance of using the language to solve problems.
Conversely, it is possible to emphasize problem solving to the extent that
using a particular language to solve problems becomes almost incidental.
The intent of this text is to provide a happy medium between these ap
proaches. Students should understand language concepts and subse
quently be able to use them to solve problems.
Overview and As with the first edition, the material in Chapters 1-4 is presented at a
Organization deliberate pace. If students in the class have already had some program
ming experience, these chapters may be covered rapidly. However, stu
dents must be able to solve problems using top-down design with stepwise
refinement. Using this approach, students will be exposed to the concept
and to restricted use of subprograms very early in the course. If this is
overlooked,s tudents will have difficulty designing solutions to more com
plex problems later.
Throughout the text, I have attempted to explain and develop concepts
carefully. These are illustrated by frequent examples and diagrams. New
concepts are then used in complete programs to show how they aid in
solving problems. An early and consistent emphasis has been placed on
good writing habits and on producing neat, attractive output. I firmly
believe program documentation and readability are important. Thus, I
frequently discuss them in the text, and I offer style tips where appropriate.
This text should provide a complete one-semester course in Pascal.
There are at least three general scenarios for which this text would be
appropriate.
1. A deliberately paced, thorough presentation of concepts would al
low you to get through records and/or files in a one-semester
course.
XI
xii Preface
2. An accelerated pace with students who have previous computing
experience would allow you to get into Chapter 15 in a one-
semester course.
3. A deliberate pace with a thorough presentation would allow you
to present the material in Chapters 1-15 in a two-quarter
sequence.
Subprograms have been treated in a manner slightly different from other
presentations. Procedures for headings only (no parameters) are intro
duced in Chapter 4. Formal development of procedures is then delayed
until Chapter 7 after conditional statements and loops have been dis
cussed. At this stage, students are better able to understand the use of
parameters. All subsequent work utilizes subprograms in problem solution
and program design.
In this edition, Chapter 8 presents text files as well as user-defined data
types. Since larger data sets are typically used with arrays and files, it is
assumed that most data will be read from data files (rather than entered
interactively) after this chapter.
Chapters 9 and 10 develop arrays. Due to the significance of this con
cept, these chapters contain numerous examples, illustrations, and ap
plications. A selection sort has been used to sort array elements. However,
a bubble sort and an insertion sort have been developed in Chapter 13,
and either could be used in place of the sorting algorithm presented in
Section 9.3. Records and files are discussed in Chapters 11 and 12, re
spectively. Their placement there is traditional. These chapters, combined
with Chapters 9 and 10, present a detailed treatment of static data structures.
Chapter 13 is an optional chapter that discusses recursion, sorting, and
merging. Recursion has been moved to this chapter so that an expanded
presentation would be more appropriately placed. This also allows the
quick sort to be developed. For advanced classes, material in this chapter
could be used to motivate additional work with data structures. It is
possible to use this material with preceding chapters. For example,s orting
could be discussed in conjunction with Chapter 9, and merging with
Chapter 12.
Chapter 14, Sets, could be presented any time after Chapter 8. Although
a full chapter has been devoted to this topic, a working knowledge could
be given to students in one or two days. Dynamic variables and data
structures are introduced in Chapter 15. A reasonable discussion and
development of pointers, linked lists, and binary trees is included. How
ever, a full development of these concepts would have to come from a
second course with a different text.
Pascal statements in this text conform to standard Pascal. Due to the
increasing use of Turbo Pascal with personal computers, Thrbo Pascal
references are included in the margins to indicate where Thrbo differs
from standard Pascal. Both interactive and batch mode examples are used
in this text. Interactive examples are indicated by a logo in the left margin,
as shown here.
Features This text has a number of noteworthy pedagogical features.
n Objectives—a concise list of topics and learning objectives in each
section
