Robin Jones lan Stewart

The Art of C Programming

With 42 Illustrations

Springer-Verlag New York Berlin Heidelberg

London Paris Tokyo

Contents

Preface vii

CHAPTER 1 Compilers and Interpreters 1

Editors 2 The Compilation Process 2

CHAPTER 2 The Skeleton of a C Program 5

Plus ca Change ... 6 Vive la Difference 7 Simple and Compound Statements 7 Functions That Don't Return Values 8 Returning Values 9 Main 9 Variable Types 10 Variable Scope 11 Global Variables 11 Loose Ends 12 printf 13 Comments 13

CHAPTER 3 Loops and Control Constructs 15

If 15 Conditional Expressions 16 Logical Connectives 17 Loops 17 while 17 Autoincrements 18 The sqr Function 19 do-while 22 for loops 23

x Contents

CHAPTER 4 Arithmetic and Logic

Odds and Evens Logical Operators ASCII Code AND OR XOR NOT Shifts

CHAPTER 5 Strings, Arrays, and Pointers

Strings and Pointers Arrays Declaring Arrays String Functions Left-Hand Bit Right a Bit More about Pointers Left Again Further Right Copycat

CHAPTER 6 Floats and Other Types

float double Qualifiers for int Signs and Shifts Register Variables Declaring Structures Defining Your Own Types Constants and Initializers Character Constants Handling Control Characters Defining Your Own Constants Variable Constants # include Octal and Hexadecimal Constants Initializers Initializing Pointers Declaring Function Types

Contents XI

CHAPTER 7 Input 57

Primitive Input 57 Get a Bufierfull 57 Operator Precedence 59 Strings to Numbers 60 A Feeble Excuse 63 scanf 64

CHAPTER 8 Output 66

More about printf 67 Justification 67 Printing to Memory 67 Primitive Output 68

CHAPTER 9 More About Control Constructs 70

The Conditional Operator 70 Leaping out of Loops 71 Continuing 71 Multiway Switches 72 Do Not Pass Go 73

CHAPTER 10 Recursion 75

Factorials 76 Things with Strings 77 Back-to-Front Sentences 79 In and Out 80 Reversing the Text 81 Postscript 83

CHAPTER 11 Structures 84

Playing with Structures 85 The Storeman's Mate 86 Delete 88 Add 89 Recursive Structures 90

xii Contents

CHAPTER 12 File-handling 93

I/O Redirection 94 Error Messages 94 Buffered File I/O 95 fopen 95 Creating a File 96 Once More, with Filing 97 File Access Errors 98 Random Access Files 99 The Square Table 100 Second Attempt 100 Reversing the Process 101

CHAPTER 13 Debugging 106

Common Errors 107 Runtime Errors 108 Testing a Function 109 Test Lines 110 BeThorough 112 Dormant Bugs 113

CHAPTER 14 Rational Arithmetic 117

Fixing the Problem 118 Overflow 119 A Practical Organization 120 Functions 121 Double or Nothing 122 Portability Considerations 125 Lies, Damned Lies and Computer Programs 126 Subtraction 126 Multiplication 127 Division 127 The Conversion Routines 127 And Now the Bad News ... 129 Postscript 131

CHAPTER 15 Implementing Turtle Graphics... 132

Turning Turtle 133 But First, The Snags ... 134 Triggery—Pokery 134 The Turtle Commands 137 Turtle Incorporated 139

Contents xui

Seeketh after a Sine 140 A Trig Suite in C 143

CHAPTER 16 . . . and Using Them 145

Rectangles 146 Fan-Dancing 147 Polygons 149 Circle 151 Stars 151 Spirals 151 The Koch Snowflake 152 Afterthoughts... 155

CHAPTER 17 Random Thoughts 157

Some Basic Ideas 158 Testing "Randomness" 159 The Numerical Connection 160 Linear Feedback Shift Registers 162 A Practical Program 163

APPENDIX 1 Loose Ends 169

APPENDIX 2 Quick Reference Guide 176

Index 183