Beginning C Beginning

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Beginning C: From Novice to Professional,
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C
Dear Reader,
e
If you aspire to be a programmer, C is an excellent choice for your first language. g
It’s more compact than most programming languages, which means there’s less
to remember; but in spite of that, C is extremely powerful, and many operating i
n
systems are written in C. It’s also supported in a wide variety of computer envi-
Author of ronments, which means that there are relatively few computers that do not n
have a C compiler available.
Ivor Horton’s Beginning i
My objective with this book is to take you from beginner to a good level of
ANSI C++:The Complete n
Language competence in C programming. My book will teach you the complete funda- Beginning
mentals of the C language and how to program. All you need in addition to this g
Ivor Horton’s Beginning
book is one of the widely available free or commercial standard C compilers
Java 2,JDK 5 Edition
and you’ll soon be writing real C programs. C
Ivor Horton’s Beginning
I’ll teach you C from first principles without assuming any prior knowledge of
Visual C++ 2005
programming, and I’ll explain all the elements of the C language, using step-by-
Beginning Visual C++ 6
stepexamples. I’ll help you increase your programming skills by guiding you
through the development of fully working C applications that apply what you’ve
learned in a practical context. You’ll also gain confidence in programming
through working examples that you’ll create and execute yourself.
Learning C is a challenge, but I’m sure you’ll have great fun doing it, and you’ll
find it very rewarding. As long as you have the enthusiasm and commitment to
complete the book, you’ll get the personal satisfaction of having achieved
something really worthwhile. You will also be taking a major step into the world
of real C programming. From Novice to Professional
Ivor Horton
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Beginning C
From Novice to Professional,
Fourth Edition
■ ■ ■
Ivor Horton
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Beginning C: From Novice to Professional, Fourth Edition
Copyright © 2006 by Ivor Horton
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This book is for the latest member of the family, Henry James Gilbey, who joined
us on July 14, 2006. He hasn’t shown much interest in programming so far,
but he did smile when I asked him about it so I expect he will.
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Horton_735-4FRONT.fm Page v Saturday, September 23, 2006 5:08 AM
Contents at a Glance
About the Author . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xix
Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xxi
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xxiii
■ CHAPTER 1 Programming in C . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
■ CHAPTER 2 First Steps in Programming . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
■ CHAPTER 3 Making Decisions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81
■ CHAPTER 4 Loops . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 129
■ CHAPTER 5 Arrays . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 175
■ CHAPTER 6 Applications with Strings and Text . . . . . . . . . . . . . . . . . . . . . . . . . . . 203
■ CHAPTER 7 Pointers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 241
■ CHAPTER 8 Structuring Your Programs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 295
■ CHAPTER 9 More on Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 329
■ CHAPTER 10 Essential Input and Output Operations . . . . . . . . . . . . . . . . . . . . . . . 373
■ CHAPTER 11 Structuring Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 409
■ CHAPTER 12 Working with Files . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 467
■ CHAPTER 13 Supporting Facilities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 529
■ APPENDIX A Computer Arithmetic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 557
■ APPENDIX B ASCII Character Code Definitions . . . . . . . . . . . . . . . . . . . . . . . . . . . . 565
■ APPENDIX C Reserved Words in C . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 571
■ APPENDIX D Input and Output Format Specifications . . . . . . . . . . . . . . . . . . . . . . 573
■ INDEX . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 579
v
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Contents
About the Author . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xix
Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xxi
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xxiii
■ CHAPTER 1 Programming in C . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Creating C Programs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Editing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Compiling. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
Linking. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Executing. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Creating Your First Program . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
Editing Your First Program . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Dealing with Errors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Dissecting a Simple Program . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Comments. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Preprocessing Directives. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Defining the main() Function. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Keywords. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
The Body of a Function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Outputting Information. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Arguments. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Control Characters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Developing Programs in C . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Understanding the Problem. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Detailed Design. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Implementation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Testing. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Functions and Modular Programming . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Common Mistakes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
Points to Remember . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Exercises . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
vii
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viii ■ CONTENTS
■ CHAPTER 2 First Steps in Programming . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
Memory in Your Computer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
What Is a Variable? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Variables That Store Numbers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
Integer Variables. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
Naming Variables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
Using Variables. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
Initializing Variables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
Arithmetic Statements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
Variables and Memory . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
Integer Variable Types . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
Unsigned Integer Types . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
Using Integer Types . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
Specifying Integer Constants. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
Floating-Point Values . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
Floating-Point Variables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
Division Using Floating-Point Values . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
Controlling the Number of Decimal Places . . . . . . . . . . . . . . . . . . . . 44
Controlling the Output Field Width . . . . . . . . . . . . . . . . . . . . . . . . . . . 44
More Complicated Expressions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
Defining Constants . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
Knowing Your Limitations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50
Introducing the sizeof Operator. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52
Choosing the Correct Type for the Job . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54
Explicit Type Conversion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57
Automatic Conversion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57
Rules for Implicit Conversions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57
Implicit Conversions in Assignment Statements. . . . . . . . . . . . . . . . 58
More Numeric Data Types . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59
The Character Type . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59
Character Input and Character Output. . . . . . . . . . . . . . . . . . . . . . . . 60
The Wide Character Type. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63
Enumerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64
Variables to Store Boolean Values . . . . . . . . . . . . . . . . . . . . . . . . . . . 66
The Complex Number Types. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67
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■ CONTENTS ix
The op= Form of Assignment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70
Mathematical Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71
Designing a Program . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72
The Problem . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72
The Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73
The Solution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75
Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79
Exercises . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80
■ CHAPTER 3 Making Decisions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81
The Decision-Making Process . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81
Arithmetic Comparisons. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82
Expressions Involving Relational Operators. . . . . . . . . . . . . . . . . . . . 82
The Basic if Statement. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82
Extending the if Statement: if-else. . . . . . . . . . . . . . . . . . . . . . . . . . . 86
Using Blocks of Code in if Statements. . . . . . . . . . . . . . . . . . . . . . . . 88
Nested if Statements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89
More Relational Operators. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92
Logical Operators . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 96
The Conditional Operator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99
Operator Precedence: Who Goes First? . . . . . . . . . . . . . . . . . . . . . . 102
Multiple-Choice Questions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 106
Using else-if Statements for Multiple Choices . . . . . . . . . . . . . . . . 106
The switch Statement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 107
The goto Statement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 115
Bitwise Operators . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 116
The op= Use of Bitwise Operators . . . . . . . . . . . . . . . . . . . . . . . . . . 119
Using Bitwise Operators. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 119
Designing a Program . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 122
The Problem . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 122
The Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 122
The Solution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 123
Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 126
Exercises . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 126