Table Of Content

Computer Science & Engineering I n “… an excellent entryway into practical software development practices … I t e wished I had this book some 20 years ago … the hands-on examples … are eye r opening. I recommend this book to anyone who needs to write software beyond m the tinkering level.” —From the Foreword by Gerhard Klimeck, Reilly Director of the Center for Predic- e tive Materials and Devices and the Network for Computational Nanotechnology d and Professor of Electrical and Computer Engineering, Purdue University; Fellow i a of the IOP, APS, and IEEE t e “This well-written book provides the necessary tools and practical skills to turn students into seasoned programmers. It not only teaches students how to write C good programs but, more uniquely, also teaches them how to avoid writing bad P programs. The inclusion of Linux operations and Versioning control as well as the coverage of applications and IDE build students’ confidence in taking control over r o large-scale software developments.” g —Siau Cheng Khoo, Ph.D., National University of Singapore r a “This book is unique in that it covers the C programming language from a bottom- m up perspective, which is rare in programming books. … students immediately understand how the language works from a very practical and pragmatic per- m spective.” —Niklas Elmqvist, Ph.D., Associate Professor and Program Director, Master of i n Science in Human–Computer Interaction, University of Maryland g Intermediate C Programming provides a stepping-stone for intermediate-level students to go from writing short programs to writing real programs well. It shows students how to identify and eliminate bugs, write clean code, share code with others, and use standard Linux-based tools, such as ddd and valgrind. The text enhances their programming skills by explaining programming concepts and comparing common mistakes with correct programs. It also discusses how to use debuggers and the strategies for debugging as well as studies the connection L between programming and discrete mathematics. u K25074 www.crcpress.com K25074_cover.indd 1 5/13/15 8:43 AM Intermediate C Programming TThhiiss ppaaggee iinntteennttiioonnaallllyy lleefftt bbllaannkk Intermediate C Programming Yung-Hsiang Lu Purdue University West Lafayette, IN, USA CRC Press Taylor & Francis Group 6000 Broken Sound Parkway NW, Suite 300 Boca Raton, FL 33487-2742 © 2015 by Taylor & Francis Group, LLC CRC Press is an imprint of Taylor & Francis Group, an Informa business No claim to original U.S. Government works Version Date: 20150407 International Standard Book Number-13: 978-1-4987-1164-7 (eBook - PDF) This book contains information obtained from authentic and highly regarded sources. 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Visit the Taylor & Francis Web site at http://www.taylorandfrancis.com and the CRC Press Web site at http://www.crcpress.com Contents List of Figures xiii List of Tables xix Foreword xxi Preface xxiii Author, Reviewers, and Artist xxvii Rules in Software Development xxix Source Code xxxi I Computer Storage: Memory and File 1 1 Program Execution 3 1.1 Compile . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 1.2 Redirect Output . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 2 Stack Memory 9 2.1 Values and Addresses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 2.2 Stack . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 2.3 The Call Stack . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 2.3.1 The Return Location. . . . . . . . . . . . . . . . . . . . . . . . . . . 11 2.3.2 Function Arguments . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 2.3.3 Local Variables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 2.3.4 Value Address . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 2.3.5 Arrays . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 2.3.6 Retrieving Addresses . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 2.4 Visibility . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 2.5 Exercises . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24 2.5.1 Draw Call Stack I . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24 2.5.2 Draw Call Stack II . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 2.5.3 Addresses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 2.6 Answers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26 2.6.1 Draw Call Stack I . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26 2.6.2 Draw Call Stack II . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26 2.6.3 Addresses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27 2.7 Examine the Call Stack with DDD . . . . . . . . . . . . . . . . . . . . . . . 27 v vi Contents 3 Prevent, Detect, and Remove Bugs 33 3.1 Developing Software (cid:2)= Coding . . . . . . . . . . . . . . . . . . . . . . . . . 33 3.1.1 Before coding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34 3.1.2 During coding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34 3.1.3 After coding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35 3.2 Common Mistakes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35 3.2.1 Uninitialized Variables . . . . . . . . . . . . . . . . . . . . . . . . . . 36 3.2.2 Wrong Array Indexes . . . . . . . . . . . . . . . . . . . . . . . . . . 36 3.2.3 Wrong Types . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36 3.3 Post-Execution and Interactive Debugging . . . . . . . . . . . . . . . . . . 36 3.4 Separate Testing Code from Production Code . . . . . . . . . . . . . . . . 37 4 Pointers 39 4.1 Scope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39 4.2 The Swap Function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41 4.3 Pointers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43 4.4 The Swap Function Revisited . . . . . . . . . . . . . . . . . . . . . . . . . . 47 4.5 Type Errors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50 4.6 Arrays and Pointers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51 4.7 Type Rules . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54 4.8 Pointer Arithmetic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55 4.9 Exercises . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59 4.9.1 Swap Function 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59 4.9.2 Swap Function 2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59 4.9.3 Swap Function 3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60 4.9.4 Swap Function 4 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60 4.9.5 Swap Function 5 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61 4.9.6 15,552 Variations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61 4.10 Answers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62 4.10.1 Swap Function 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62 4.10.2 Swap Function 2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63 4.10.3 Swap Function 3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63 4.10.4 Swap Function 4 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63 4.10.5 Swap Function 5 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63 5 Writing and Testing Programs 65 5.1 Distinct Array Elements . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65 5.1.1 main Function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66 5.1.2 areDistinctFunction . . . . . . . . . . . . . . . . . . . . . . . . . . 67 5.1.3 Compiling and Linking. . . . . . . . . . . . . . . . . . . . . . . . . . 68 5.1.4 make . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69 5.2 Test Using Makefile . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71 5.2.1 Generating Test Cases . . . . . . . . . . . . . . . . . . . . . . . . . . 72 5.2.2 Redirecting Output . . . . . . . . . . . . . . . . . . . . . . . . . . . 72 5.2.3 Use diff to Compare Output . . . . . . . . . . . . . . . . . . . . . . 73 5.2.4 Adding Tests to Makefile . . . . . . . . . . . . . . . . . . . . . . . . 73 5.3 Invalid Memory Access . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75 5.4 Using valgrindto Check Memory Access Errors . . . . . . . . . . . . . . . 77 5.5 Test Coverage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79 5.6 Limit Core Size . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82 5.7 Programs with Infinite Loops . . . . . . . . . . . . . . . . . . . . . . . . . . 83 Contents vii 6 Strings 85 6.1 Array of Characters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85 6.2 String Functions in C . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88 6.2.1 Copy: strcpy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88 6.2.2 Compare: strcmp. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89 6.2.3 Finding Substrings: strstr . . . . . . . . . . . . . . . . . . . . . . . 90 6.2.4 Finding Characters: strchr . . . . . . . . . . . . . . . . . . . . . . . 90 6.3 Understanding argv . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91 6.4 Counting Substrings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93 7 Programming Problems and Debugging 97 7.1 Implementing String Functions . . . . . . . . . . . . . . . . . . . . . . . . . 97 7.1.1 The C Library . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 97 7.1.2 Header File . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 98 7.1.3 mystring.h . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99 7.1.4 Creating Inputs and Correct Outputs . . . . . . . . . . . . . . . . . 100 7.1.5 Makefile . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 104 7.1.6 mystring.c . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 105 7.1.7 Using const. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 106 7.2 Debugging . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 108 7.2.1 Find Infinite Loops . . . . . . . . . . . . . . . . . . . . . . . . . . . . 108 7.2.2 Find Invalid Memory Accesses . . . . . . . . . . . . . . . . . . . . . 109 7.2.3 Detect Invalid Memory Accesses . . . . . . . . . . . . . . . . . . . . 111 8 Heap Memory 113 8.1 Creating Array with malloc . . . . . . . . . . . . . . . . . . . . . . . . . . 113 8.2 The Stack and the Heap . . . . . . . . . . . . . . . . . . . . . . . . . . . . 115 8.3 Functions that Return a Heap Address . . . . . . . . . . . . . . . . . . . . 118 8.4 Two-Dimensional Arrays in C . . . . . . . . . . . . . . . . . . . . . . . . . 119 8.5 Pointers and Arguments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 122 9 Programming Problems Using Heap Memory 125 9.1 Sorting an Array . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 125 9.1.1 Generating Test Input and Expected Output . . . . . . . . . . . . . 125 9.1.2 Redirecting Input. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 127 9.1.3 Sorting Integers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 129 9.1.4 Using valgrindto Detect Memory Leaks . . . . . . . . . . . . . . . 132 9.2 Sort Using qsort . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 133 9.2.1 qsort . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 133 9.2.2 The Comparison Function . . . . . . . . . . . . . . . . . . . . . . . . 135 9.2.3 Execution Examples . . . . . . . . . . . . . . . . . . . . . . . . . . . 137 9.2.4 Sorting Strings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 138 10 Reading and Writing Files 141 10.1 Passing a File Name via argv . . . . . . . . . . . . . . . . . . . . . . . . . 141 10.2 Reading from Files . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 142 10.2.1 Reading Characters: fgetc . . . . . . . . . . . . . . . . . . . . . . . 142 10.2.2 Reading Integers: fscanf(... %d...) . . . . . . . . . . . . . . . . . 145 10.3 Writing to Files . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 147 10.4 Reading and Writing Strings . . . . . . . . . . . . . . . . . . . . . . . . . . 150 viii Contents 11 Programming Problems Using File 153 11.1 Sorting a File of Integers . . . . . . . . . . . . . . . . . . . . . . . . . . . . 153 11.2 Counting the Occurrences of Characters . . . . . . . . . . . . . . . . . . . . 155 11.3 Counting the Occurrences of a Word . . . . . . . . . . . . . . . . . . . . . . 158 11.4 How to Comment Code . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 160 II Recursion 163 12 Recursion 165 12.1 Selecting Balls with Restrictions . . . . . . . . . . . . . . . . . . . . . . . . 166 12.1.1 Balls of Two Colors . . . . . . . . . . . . . . . . . . . . . . . . . . . 166 12.1.2 Balls of Three Colors. . . . . . . . . . . . . . . . . . . . . . . . . . . 167 12.1.3 A Further Restriction . . . . . . . . . . . . . . . . . . . . . . . . . . 168 12.2 One-Way Streets . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 170 12.3 The Tower of Hanoi . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 171 12.4 Calculating Integer Partitions . . . . . . . . . . . . . . . . . . . . . . . . . 174 12.4.1 Count the Number of “1”s. . . . . . . . . . . . . . . . . . . . . . . . 175 12.4.2 Odd Numbers Only . . . . . . . . . . . . . . . . . . . . . . . . . . . 177 12.4.3 Increasing Values . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 178 12.4.4 Alternating Odd and Even Numbers . . . . . . . . . . . . . . . . . . 179 12.4.5 Generalizing the Integer Partition Problem . . . . . . . . . . . . . . 180 12.4.6 How Not to Solve the Integer Partition Problem . . . . . . . . . . . 181 13 Recursive C Functions 183 13.1 Select Balls with Restrictions . . . . . . . . . . . . . . . . . . . . . . . . . . 184 13.2 One-Way Streets . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 187 13.3 The Tower of Hanoi . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 188 13.4 Integer Partition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 190 13.5 Factorial . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 191 13.6 Fibonacci Numbers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 193 13.7 Performance Profiling with gprof . . . . . . . . . . . . . . . . . . . . . . . 199 14 Integer Partition 201 14.1 Stack and Heap Memory . . . . . . . . . . . . . . . . . . . . . . . . . . . . 202 14.2 Trace Recursive Function Calls . . . . . . . . . . . . . . . . . . . . . . . . . 210 14.3 Generating Partitions with Restrictions . . . . . . . . . . . . . . . . . . . . 213 14.3.1 Using Odd Numbers Only . . . . . . . . . . . . . . . . . . . . . . . . 214 14.3.2 Using Sequences of Increasing Numbers . . . . . . . . . . . . . . . . 215 14.3.3 Using Alternating Odd and Even Numbers . . . . . . . . . . . . . . 215 14.3.4 Using gprof and gcov to Identify Performance Bottlenecks . . . . . 216 15 Programming Problems Using Recursion 223 15.1 Binary Search . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 223 15.2 Quick Sort . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 226 15.3 Permutations and Combinations . . . . . . . . . . . . . . . . . . . . . . . . 232 15.4 Stack Sort . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 236 15.4.1 Example 1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 236 15.4.2 Example 2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 237 15.4.3 Example 3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 237 15.4.4 Example 4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 238 15.4.5 Stack Sortable . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 238 Contents ix 15.5 Tracing a Recursive Function . . . . . . . . . . . . . . . . . . . . . . . . . . 242 15.6 A Recursive Function with a Mistake . . . . . . . . . . . . . . . . . . . . . 244 III Structure 247 16 Programmer-Defined Data Types 249 16.1 Struct and Object . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 250 16.2 Passing Objects as Arguments . . . . . . . . . . . . . . . . . . . . . . . . . 253 16.3 Objects and Pointers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 256 16.3.1 Returning an Object . . . . . . . . . . . . . . . . . . . . . . . . . . . 258 16.3.2 Objects and malloc . . . . . . . . . . . . . . . . . . . . . . . . . . . 258 16.4 Constructors and Destructors . . . . . . . . . . . . . . . . . . . . . . . . . . 261 16.5 Structures within Structures . . . . . . . . . . . . . . . . . . . . . . . . . . 268 16.6 Binary Files and Objects . . . . . . . . . . . . . . . . . . . . . . . . . . . . 270 17 Programming Problems Using Structure 275 17.1 Sorting a Person Database . . . . . . . . . . . . . . . . . . . . . . . . . . . 275 17.2 Packing Decimal Digits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 281 17.2.1 Number Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 281 17.2.2 Packing Two Decimal Digits into One Byte . . . . . . . . . . . . . . 282 17.2.3 Bit Operations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 283 17.2.4 Inserting and Retrieving Decimal Digits . . . . . . . . . . . . . . . . 285 17.2.5 DecPack Program . . . . . . . . . . . . . . . . . . . . . . . . . . . . 286 17.3 Binary File and Pointer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 290 18 Linked Lists 293 18.1 Expandable Types . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 293 18.2 Linked Lists . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 294 18.3 Inserting Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 295 18.4 Searching a Linked List . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 297 18.5 Deleting from a Linked List . . . . . . . . . . . . . . . . . . . . . . . . . . . 298 18.6 Printing a Linked List . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 302 18.7 Destroying a Linked List . . . . . . . . . . . . . . . . . . . . . . . . . . . . 303 19 Programming Problems Using Linked List 307 19.1 Queues . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 307 19.2 Sorting Numbers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 308 19.3 Sparse Arrays . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 308 19.4 Reversing a Linked List . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 314 20 Binary Search Trees 317 20.1 Binary Search Tree . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 318 20.2 Inserting Data into a Binary Search Tree . . . . . . . . . . . . . . . . . . . 319 20.3 Searching a Binary Search Tree . . . . . . . . . . . . . . . . . . . . . . . . 323 20.4 Printing a Binary Tree . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 325 20.5 Deleting from a Binary Search Tree . . . . . . . . . . . . . . . . . . . . . . 327 20.6 Destroying a Binary Search Tree . . . . . . . . . . . . . . . . . . . . . . . . 330 20.7 main . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 331 20.8 Makefile . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 332 20.9 Counting the Different Shapes of a Binary Tree . . . . . . . . . . . . . . . 332