Learn to Program with C

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Kalicharan Learn to Program with

C

Learn to

Program with C

Learn to Program using the Popular

C Programming Language

—

Noel Kalicharan

Learn to Program with C

BOOKS FOR PROFESSIONALS BY PROFESSIONALS® THE EXPERT’S VOICE® IN PROGRAMMING

Learn to Program with C teaches computer programming to the complete beginner using the

native C language. As such, it assumes you have no knowledge whatsoever about programming.

The main goal of this book is to teach fundamental programming principles using C, one of the

most widely used programming languages in the world today.

We discuss only those features and statements in C that are necessary to achieve our goal.

Once you learn the principles well, they can be applied to any language. If you are worried that

you are not good at high-school mathematics, don’t be. It is a myth that you must be good at

mathematics to learn programming.

C is considered a ‘modern’ language even though its roots date back to the 1970s. Originally,

C was designed for writing ‘systems’ programs—things like operating systems, editors,

compilers, assemblers and input/output utility programs. But, today, C is used for writing all

kinds of applications as well—word processing programs, spreadsheet programs, database

management programs, accounting programs, games, robots, embedded systems/electronics

(i.e., Arduino), educational so ware—the list is endless.

• How to get started with programming using the C language

• How to use the basics of C

• How to program with sequence, selection and repetition logic

• How to work with characters

• How to work with functions

• How to use arrays

Shelve in:

Programming Languages/ANSI C

User level:

Beginning

9 781484 213728 SOURCE CODE ONLINE

ISBN 978-1-4842-1372-8

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Learn to Program

with C

Noel Kalicharan

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Learn to Program with C

Copyright © 2015 by Noel Kalicharan

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ISBN-13 (electronic): 978-1-4842-1371-1

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Lead Editor: Steve Anglin

Technical Reviewer: Rohan Walia

Editorial Board: Steve Anglin, Louise Corrigan, Jonathan Gennick, Robert Hutchinson,

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Douglas Pundick, Ben Renow-Clarke, Gwenan Spearing

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Supplementary Material section for each chapter.

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To my daughters

Anushka Nikita

and

Saskia Anyara

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v

Contents at a Glance

About the Author �����������������������������������������������������������������������������������������������������xv

About the Technical Reviewer �������������������������������������������������������������������������������xvii

Acknowledgments��������������������������������������������������������������������������������������������������xix

Preface �������������������������������������������������������������������������������������������������������������������xxi

■Chapter 1: Elementary Programming Concepts ���������������������������������������������������� 1

■Chapter 2: C – The Basics������������������������������������������������������������������������������������ 23

■Chapter 3: Programs with Sequence Logic ��������������������������������������������������������� 47

■Chapter 4: Programs with Selection Logic ���������������������������������������������������������� 65

■Chapter 5: Programs with Repetition Logic��������������������������������������������������������� 91

■Chapter 6: Characters���������������������������������������������������������������������������������������� 141

■Chapter 7: Functions ����������������������������������������������������������������������������������������� 165

■Chapter 8: Arrays ���������������������������������������������������������������������������������������������� 197

■Chapter 9: Searching, Sorting, and Merging ����������������������������������������������������� 243

■Chapter 10: Structures �������������������������������������������������������������������������������������� 279

Index��������������������������������������������������������������������������������������������������������������������� 307

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Contents

About the Author �����������������������������������������������������������������������������������������������������xv

About the Technical Reviewer �������������������������������������������������������������������������������xvii

Acknowledgments��������������������������������������������������������������������������������������������������xix

Preface �������������������������������������������������������������������������������������������������������������������xxi

■Chapter 1: Elementary Programming Concepts ���������������������������������������������������� 1

1.1 Programs, Languages, and Compilers ........................................................................ 1

1.2 How a Computer Solves a Problem ............................................................................ 3

1.2.1 Define the Problem ........................................................................................................................ 3

1.2.2 Analyze the Problem ...................................................................................................................... 4

1.2.3 Develop an Algorithm to Solve the Problem .................................................................................. 4

1.2.4 Write the Program for the Algorithm .............................................................................................. 6

1.2.5 Test and Debug the Program ......................................................................................................... 8

1.2.6 Document the Program.................................................................................................................. 9

1.2.7 Maintain the Program .................................................................................................................... 9

1.3 How a Computer Executes a Program ........................................................................ 9

1.4 Data Types ................................................................................................................ 10

1.5 Characters ................................................................................................................ 11

1.6 Welcome to C Programming ..................................................................................... 12

1.6.1 Run the Program .......................................................................................................................... 13

1.6.2 A Word on Program Layout .......................................................................................................... 14

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■ Contents

1.7 Write Output with printf ........................................................................................ 14

1.7.1 The Newline Character, \n (backslash n) .................................................................................... 15

1.7.2 Escape Sequences ...................................................................................................................... 16

1.7.3 Print the Value of a Variable ......................................................................................................... 16

1.8 Comments ................................................................................................................ 17

1.9 Programming with Variables .................................................................................... 18

■Chapter 2: C – The Basics������������������������������������������������������������������������������������ 23

2.1 Introduction .............................................................................................................. 23

2.2 The C Alphabet ......................................................................................................... 24

2.3 C Tokens ................................................................................................................... 24

2.3.1 Spacing Within a Program ........................................................................................................... 25

2.3.2 Reserved Words ........................................................................................................................... 27

2.3.3 Identifiers .................................................................................................................................... 27

2.3.4 Some Naming Conventions.......................................................................................................... 28

2.4 Basic Data Types ...................................................................................................... 28

2.5 Integer Numbers - int ............................................................................................. 29

2.5.1 Declaring Variables ...................................................................................................................... 29

2.5.2 Integer Expressions ..................................................................................................................... 29

2.5.3 Precedence of Operators ............................................................................................................. 30

2.5.4 Print an Integer Using a “Field Width” ......................................................................................... 31

2.6 Floating-Point Numbers – float and double ........................................................ 33

2.6.1 Print double and float Variables ................................................................................................ 34

2.6.2 Assignment Between double and float ..................................................................................... 36

2.6.3 Floating-Point Expressions .......................................................................................................... 36

2.6.4 Expressions with Integer and Floating-Point Values.................................................................... 37

2.6.5 Assigning double/float to int .................................................................................................. 38

2.7 Strings ...................................................................................................................... 38

2.8 The Assignment Statement ...................................................................................... 41

2.9 printf ..................................................................................................................... 42

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■ Contents

■Chapter 3: Programs with Sequence Logic ��������������������������������������������������������� 47

3.1 Introduction .............................................................................................................. 47

3.2 Read Data Supplied by a User .................................................................................. 47

3.3 scanf ....................................................................................................................... 50

3.3.1 Read Data Into a float Variable ................................................................................................. 52

3.3.2 Read Data Into a double Variable ............................................................................................... 52

3.4 Read Strings ............................................................................................................. 54

3.5 Examples .................................................................................................................. 55

3.5.1 Problem 1 - Average .................................................................................................................... 55

3.5.2 Problem 2 - Square ..................................................................................................................... 56

3.5.3 Problem 3 - Banking .................................................................................................................... 57

3.5.4 Problem 4 – Tickets ..................................................................................................................... 60

■Chapter 4: Programs with Selection Logic ���������������������������������������������������������� 65

4.1 Introduction .............................................................................................................. 65

4.2 Boolean Expressions ................................................................................................ 65

4.2.1 AND, &&........................................................................................................................................ 66

4.2.2 OR, || ............................................................................................................................................ 67

4.2.3 NOT, ! ........................................................................................................................................... 68

4.3 The if Construct ...................................................................................................... 69

4.3.1 Find the Sum of Two Lengths ...................................................................................................... 72

4.4 The if...else Construct ....................................................................................... 75

4.4.1 Calculate Pay............................................................................................................................... 77

4.5 On Program Testing .................................................................................................. 80

4.6 Symbolic Constants .................................................................................................. 80

4.6.1 The #define Directive .................................................................................................................. 81

4.6.2 Example – Symbolic Constants ................................................................................................... 82

4.7 More Examples ......................................................................................................... 83

4.7.1 Print a Letter Grade ..................................................................................................................... 83

4.7.2 Classify a Triangle ........................................................................................................................ 85

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■ Contents

■Chapter 5: Programs with Repetition Logic��������������������������������������������������������� 91

5.1 Introduction .............................................................................................................. 91

5.2 The while Construct ................................................................................................ 91

5.2.1 Highest Common Factor .............................................................................................................. 96

5.3 Keep a Count ............................................................................................................ 97

5.3.1 Find Average................................................................................................................................ 99

5.4 Increment and Decrement Operators ..................................................................... 100

5.5 Assignment Operators ............................................................................................ 101

5.6 Find Largest ........................................................................................................... 102

5.7 Find Smallest ......................................................................................................... 105

5.8 Read Data from a File ............................................................................................. 106

5.8.1 fscanf...................................................................................................................................... 108

5.8.2 Find Average of Numbers in a File ............................................................................................. 108

5.9 Send Output to a File .............................................................................................. 110

5.9.1 fprintf......................................................................................................................................... 111

5.10 Payroll .................................................................................................................. 112

5.11 The for Construct ................................................................................................ 118

5.11.1 The for Statement in C ........................................................................................................... 120

5.11.2 A Bit of Aesthetics ................................................................................................................... 125

5.12 Multiplication Tables ............................................................................................. 125

5.13 Temperature Conversion Table ............................................................................. 129

5.14 Expressive Power of for ...................................................................................... 131

5.15 The do...while Statement ................................................................................ 132

5.15.1 Highest Common Factor .......................................................................................................... 133

5.15.2 Interest at the Bank ................................................................................................................. 134

■Chapter 6: Characters���������������������������������������������������������������������������������������� 141

6.1 Character Sets ........................................................................................................ 141

6.2 Character Constants and Values............................................................................. 142

6.3 The Type char ........................................................................................................ 143

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6.4 Characters in Arithmetic Expressions .................................................................... 143

6.4.1 Uppercase To/From Lowercase ................................................................................................. 144

6.5 Read and Print Characters ..................................................................................... 145

6.6 Count Characters .................................................................................................... 152

6.6.1 Count Characters in a Line ........................................................................................................ 153

6.7 Count Blanks in a Line of Data ............................................................................... 153

6.8 Compare Characters ............................................................................................... 155

6.9 Read Characters from a File ................................................................................... 156

6.10 Write Characters to a File ..................................................................................... 157

6.10.1 Echo Input, Number Lines ........................................................................................................ 157

6.11 Convert Digit Characters to Integer ...................................................................... 161

■Chapter 7: Functions ����������������������������������������������������������������������������������������� 165

7.1 About Functions ...................................................................................................... 165

7.2 skipLines ............................................................................................................ 166

7.3 A Program with a Function ..................................................................................... 167

7.3.1 The Function Header .................................................................................................................. 168

7.3.2 How a Function Gets Its Data .................................................................................................... 169

7.4 max ......................................................................................................................... 170

7.5 Print the Day ........................................................................................................... 173

7.6 Highest Common Factor ......................................................................................... 175

7.6.1 Using HCF to Find LCM .............................................................................................................. 177

7.7 factorial .................................................................................................................. 178

7.7.1 Using Factorial ........................................................................................................................... 181

7.7.2 Combinations ............................................................................................................................. 182

7.8 Job Charge ............................................................................................................. 184

7.9 Calculate Pay .......................................................................................................... 185

7.10 Sum of Exact Divisors .......................................................................................... 186

7.10.1 Classify Numbers ..................................................................................................................... 186

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7.11 Some Character Functions ................................................................................... 188

7.11.1 Position of a Letter in the Alphabet ......................................................................................... 189

7.12 Fetch the Next Integer .......................................................................................... 191

■Chapter 8: Arrays ���������������������������������������������������������������������������������������������� 197

8.1 Simple vs Array Variable ......................................................................................... 197

8.2 Array Declaration .................................................................................................... 198

8.3 Store Values in an Array ......................................................................................... 199

8.3.1 About Not Using Element 0 ........................................................................................................ 203

8.4 Average and Differences from Average .................................................................. 203

8.5 Letter Frequency Count .......................................................................................... 206

8.6 Making Better Use of fopen .................................................................................. 209

8.7 Array as Argument to a Function ............................................................................ 211

8.8 String – Array of Characters ................................................................................... 213

8.8.1 Reverse the Characters in a String ........................................................................................... 217

8.9 Palindrome ............................................................................................................. 220

8.9.1 A Better Palindrome Function .................................................................................................... 223

8.10 Array of Strings – Name of Day Revisited ............................................................ 225

8.11 A Flexible getString Function ............................................................................... 228

8.12 A Geography Quiz Program................................................................................... 230

8.13 Find the Largest Number ...................................................................................... 233

8.14 Find the Smallest Number .................................................................................... 235

8.15 A Voting Problem .................................................................................................. 235

■Chapter 9: Searching, Sorting, and Merging ����������������������������������������������������� 243

9.1 Sequential Search .................................................................................................. 243

9.2 Selection Sort ......................................................................................................... 246

9.2.1 Analysis of Selection Sort .......................................................................................................... 252

9.3 Insertion Sort .......................................................................................................... 252

9.3.1 Analysis of Insertion Sort ........................................................................................................... 258

9.3.2 Insert an Element in Place ......................................................................................................... 259

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9.4 Sort an Array of Strings .......................................................................................... 260

9.4.1 Variable-Length Arrays .............................................................................................................. 260

9.5 Sort Parallel Arrays ................................................................................................. 262

9.6 Binary Search ......................................................................................................... 264

9.7 Word Frequency Count ........................................................................................... 266

9.8 Merge Sorted Lists ................................................................................................. 271

9.8.1 Implement the Merge ................................................................................................................ 273

■Chapter 10: Structures �������������������������������������������������������������������������������������� 279

10.1 The Need for Structures ....................................................................................... 279

10.2 How to Declare a Structure .................................................................................. 280

10.2.1 typedef.................................................................................................................................. 283

10.3 Array of Structure ................................................................................................. 285

10.4 Search an Array of Structure ................................................................................ 286

10.5 Sort an Array of Structure .................................................................................... 287

10.6 Read, Search, and Sort a Structure ...................................................................... 288

10.7 Nested Structures ................................................................................................ 292

10.8 Work with Fractions ............................................................................................. 293

10.8.1 Manipulate Fractions ............................................................................................................... 294

10.9 A Voting Problem .................................................................................................. 295

10.10 Pass Structures to Functions ............................................................................. 304

Index��������������������������������������������������������������������������������������������������������������������� 307

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About the Author

Dr. Noel Kalicharan is a Senior Lecturer in Computer Science

at the University of the West Indies, St. Augustine, Trinidad.

For 40 years, he has taught programming courses to people at all

levels. He has been teaching computer science at the University

since 1976. In 1988, he developed and hosted a 26-programme

television series entitled Computers - Bit by Bit. Among other

things, this series taught programming to the general public.

He is always looking for innovative ways to teach logical thinking

skills which go hand in hand with programming skills. His efforts

resulted in two games - BrainStorm! and Not Just Luck - which

won him the Prime Minister’s Award for Invention and Innovation

in 2000 and 2002, respectively. He is a Computer Science author

for Cambridge University Press which published his international

successes, Introduction to Computer Studies and C By Example.

The C book is ranked among the best in the world for learning the

C programming language. It has received glowing reviews from readers as far away as Australia,

Canada, India and Scotland. This book is written in a more leisurely style. Born in Lengua Village,

Princes Town, Trinidad, he received his primary education at the Lengua Presbyterian School

and his secondary education at Naparima College. He is a graduate of The University of the

West Indies, Jamaica, the University of British Columbia, Canada and The University of the

West Indies, Trinidad.

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About the Technical Reviewer

Rohan Walia is a Senior Software Consultant with extensive

experience in client-server, web-based, and enterprise application

development. He is an Oracle Certified ADF Implementation

Specialist and a Sun Certified Java Programmer. Rohan is

responsible for designing and developing end-to-end applications

consisting of various cutting-edge frameworks and utilities.

His areas of expertise are Oracle ADF, Oracle WebCenter, Fusion,

Spring, Hibernate, and Java/J2EE. When not working, Rohan loves

to play tennis, hike, and travel. Rohan would like to thank his wife,

Deepika Walia, for using all her experience and expertise to review

this book.

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xix

Acknowledgements

I would like to express my deepest appreciation to Shellyann Sooklal for the time and care she

took in reading the manuscript, oftentimes finding subtle errors that a less critical eye would have

overlooked.

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