Beginning C
From Beginner to Pro
7th ed.
German
German Gonzalez-Morris Santiago, Chile
Ivor Horton
STRATFORD UPON AVON, UK
ISBN 979-8-8688-0148-8 e-ISBN 979-8-8688-0149-5
https://doi.org/10.1007/979-8-8688-0149-5
© German Gonzalez-Morris and Ivor Horton 2013, 2020, 2024
This work is subject to copyright. All rights are solely and exclusively licensed by the Publisher, whether the whole or part of the material is concerned, speci ically the rights of translation, reprinting, reuse of illustrations, recitation, broadcasting, reproduction on micro ilms or in any other physical way, and transmission or information storage and retrieval, electronic adaptation, computer software, or by similar or dissimilar methodology now known or hereafter developed.
The use of general descriptive names, registered names, trademarks, service marks, etc. in this publication does not imply, even in the absence of a speci ic statement, that such names are exempt from the relevant protective laws and regulations and therefore free for general use.
The publisher, the authors, and the editors are safe to assume that the advice and information in this book are believed to be true and accurate at the date of publication. Neither the publisher nor the authors or the editors give a warranty, expressed or implied, with respect to the material contained herein or for any errors or omissions that may have been made. The publisher remains neutral with regard to jurisdictional claims in published maps and institutional af iliations.
This Apress imprint is published by the registered company APress Media, LLC, part of Springer Nature. The registered company address is: 1 New York Plaza, New York, NY 10004, U.S.A.
To my family, Patricia, Raimundo, and Gregorio
—German Gonzalez-Morris
In memory of my beautiful wife, Eve
—Ivor Horton
Introduction
Welcome to Beginning C: From Beginner to Pro, Seventh Edition. With this book, you can become a competent C programmer using the latest version of the C language. In many ways, C is an ideal language with which to learn programming. It’s very compact, so there isn’t a lot of syntax to learn before you can write real applications. In spite of its conciseness, it’s extremely powerful and is used by professionals in many different areas. The power of C is such that it can be applied at all levels, from developing device drivers and operating system components to creating large-scale applications. A relatively new area for C is in application development for mobile phones.
C compilers are available for virtually every kind of computer, so when you’ve learned C, you’ll be equipped to program in just about any context. Once you know C, you have an excellent base from which you can build an understanding of the object-oriented C++.
My objective in this book is to minimize what I think are the three main hurdles the aspiring programmer must face: coming to grips with the jargon that pervades every programming language, understanding how to use the language elements (as opposed to merely knowing what they are), and appreciating how the language is applied in a practical context.
Jargon is an invaluable and virtually indispensable means of communication for the expert professional as well as the competent amateur, so it can’t be avoided. My approach is to ensure that you understand the jargon and get comfortable using it in context. In this way, you’ll be able to more effectively use the documentation that comes along with the typical programming product and also feel comfortable reading and learning from the literature that surrounds most programming languages.
Comprehending the syntax and effects of the language elements is obviously an essential part of learning C, but appreciating how the language features work and how they are used is equally important. Rather than just using code fragments, I provide you with practical working examples in each chapter that show how the language features can be applied to speci ic problems. These examples provide a basis for you to experiment and see the effects of changing the code.
Your understanding of programming in context needs to go beyond the mechanics of applying individual language elements. To help you gain this understanding, I conclude most chapters with a more complex program that applies what you’ve learned in the chapter. These programs will help you gain the competence and con idence to develop your own applications and provide you with insight into how you can apply language elements in combination and on a larger scale. Most importantly, they’ll give you an idea of what’s involved in designing real programs and managing real code.
The book’s spirit is to start from a beginner and inish as a pro. Nevertheless, as usual, technology is broad and complex for each part of the knowledge. Therefore, there is always a space to learn more profoundly about each topic. I encourage you to keep learning and researching each aspect you ind more interesting (new knowledge is always good).
It’s important to realize a few things that are true for learning any programming language. First, there is quite a lot to learn, but this means you’ll gain a greater sense of satisfaction when you’ve mastered it. Second, it’s great fun, so you really will enjoy it. Third, you can only learn programming by doing it, and this book helps you along the way. Finally, it’s certain you will make a lot of mistakes and get frustrated from time to time during the learning process. When you think you are completely stuck, you just need to be persistent. You will eventually experience that eureka moment and realize it wasn’t as dif icult as you thought.
How to Use This Book
Because I believe in the hands-on approach, you’ll write your irst programs almost immediately. Every chapter has several complete programs that put theory into practice, and these are key to the book. You should type in and run all the examples that appear in the text because the very act of typing them in is a tremendous memory aid. You should also attempt all the exercises that appear at the end of each chapter. When you get a program to work for the irst time— particularly when you’re trying to solve your own problems—you’ll
ind that the great sense of accomplishment and progress makes it all worthwhile.
The pace is gentle at the start, but you’ll gain momentum as you get further into the subject. Each chapter covers quite a lot of ground, so take your time and make sure you understand everything before moving on. Experimenting with the code and trying out your own ideas are important parts of the learning process. Try modifying the programs and see what else you can make them do—that’s when it gets really interesting. And don’t be afraid to try things out—if you don’t understand how something works, just type in a few variations and see what happens. It doesn’t matter if it’s wrong. You’ll ind you often learn a lot from getting it wrong. A good approach is to read each chapter through, get an idea of its scope, and then go back and work through all the examples.
You might ind some of the end-of-chapter programs quite dif icult. Don’t worry if it’s not all completely clear on the irst try. There are bound to be bits that you ind hard to understand at irst because they often apply what you’ve learned to rather complicated problems. If you really get stuck, you can skip the end-of-chapter exercises, move on to the next chapter, and come back to them later. You can even go through the entire book without worrying about them. However, if you can complete the exercises, it shows you are making real progress.
Who This Book Is For
Beginning C, Seventh Edition is designed to teach you how to write useful programs in C as quickly and easily as possible. By the end of Beginning C, you’ll have a thorough grounding in programming the C language. This is a tutorial for those of you who’ve done a little bit of programming before, understand the concepts behind it, and want to further your knowledge by learning C. However, no previous programming knowledge on your part is assumed, so if you’re a newcomer to programming, the book will still work for you.
What You Need to Use This Book
To use this book, you’ll need a computer with a C compiler and library installed, so you can execute the examples, and a program text editor for preparing your source code iles. The compiler you use should provide good support for the current international standard for the C language, C23 (ISO/IEC 9899:2023), which is a signi icant update to replace the C17 standard, commonly referred to as C23 or C2x. You’ll also need an editor for creating and modifying your code. You can use any plain text editor such as Notepad++ or vi to create your source program iles. However, you’ll get along better if your editor is designed for editing C code.
I can suggest two sources for a suitable C compiler, both of which are freeware:
The GNU C compiler, GCC, is available from gcc.gnu.org and supports a variety of operating system environments (version 13+).
The Pelles C compiler for Microsoft Windows is downloadable from www.smorgasbordet.com/pellesc/ and includes an excellent integrated development environment (IDE) (version 12+).
Conventions Used
I use a number of different styles of text and layout in the book to help differentiate between the different kinds of information. For the most part, their meanings will be obvious. Program code will appear like this:
int main(void)
{
printf("Beginning C\n"); return 0; }
When a code fragment is a modi ied version of a previous instance, I occasionally show the lines that have changed in bold type like this:
int main(void)
{
printf("Beginning C by Ivor Horton & German Gonzalez-Morris\n"); return 0; }
When code appears in the text, it has a different typestyle that looks like this: double.
I’ll use different types of “brackets” in the program code. They aren’t interchangeable, and their differences are very important. I’ll refer to the symbols ( ) as parentheses, the symbols { } as braces, and the symbols [ ] as square brackets.
Important new words in the text are shown in italic like this. Any source code or other supplementary material referenced by the author in this book is available to readers on GitHub via the book’s product page, located at www.apress.com/9781484259757. For more detailed information, please visit www.apress.com/sourcecode.
Any source code or other supplementary material referenced by the author in this book is available to readers on GitHub. For more detailed information, please visit https://www.apress.com/gp/services/source-code.
Acknowledgments
I am profoundly grateful to Patricia Cruces, my life partner, whose in inite patience, unwavering support, and boundless love have been my constant companions through every challenge and triumph. Her presence has been a source of inspiration, making this journey more meaningful and ful illing.
To my sons, Raimundo and Gregorio, I owe immeasurable thanks for being the bright sparks of joy and inspiration in my life. Your happiness reminds me of what truly matters, and your enthusiasm ills me with determination.
To my parents, German and Felicia Morris, who have been my pillars of strength, providing both love and guidance and invaluable educational opportunities.
To my friend Daniel Lagos, a great engineer, whose constructive criticism, suggestions, exchange of ideas, and feedback have not only helped my understanding with his input but have inspired me to explore alternative approaches and support continuous improvement. I appreciate the collaborative spirit demonstrated by my university classmates Alejandro Cuevas and Fernando Castillo, as their diverse perspectives have contributed to more comprehensive, real-world examples and practical applications, particularly to my lessons on C language pointers.
I am grateful for the support and opportunities provided to me by the entire Apress team, especially Melissa Duffy and Sowmya Thodur. Their guidance and advice have been invaluable. I also want to thank Megan Hirni, the technical reviewer, for her clever feedback, suggestions, and corrections.
—German Gonzalez-Morris
Table of Contents
Chapter 1: Programming in C
The C Language
The Standard Library
Learning C
Creating C Programs
Editing
Compiling
Linking
Executing
Creating Your First Program
Editing Your First Program
Dealing with Errors
Dissecting a Simple Program
Comments
Preprocessing Directives
De ining the main() Function
Keywords
The Body of a Function
Outputting Information
Function Arguments
Control Characters
Trigraph Sequences
The Preprocessor
Developing Programs in C
Understanding the Problem
Detailed Design
Implementation
Testing
Functions and Modular Programming
Common Mistakes
Points to Remember
Summary
Chapter 2: First Steps in Programming
Memory in Your Computer
What Is a Variable?
Naming Variables
Variables That Store Integers
Using Variables
Initializing Variables
More on Division with Integers
Unary Operators
Unary Minus Operator
Variables and Memory
Signed Integer Types
Unsigned Integer Types
Specifying Integer Constants
Binary Integer Constants
Working with Floating-Point Numbers
Floating-Point Number Representation
Floating-Point Variables
Division Using Floating-Point Values
Controlling the Number of Decimal Places in the Output
Controlling the Output Field Width
More Complicated Expressions
Checked Integer Arithmetic
constexpr
De ining Named Constants
Knowing Your Limitations
Introducing the sizeof Operator
Choosing the Correct Type for the Job
Explicit Type Conversion
Automatic Conversions
Rules for Implicit Conversions
Implicit Conversions in Assignment Statements
Type Inference
typeof
More Numeric Data Types
Character Type
Character Input and Character Output
Enumerations
Choosing Enumerator Values
Unnamed Enumeration Types
Variables That Store Boolean Values
The op= Form of Assignment
Mathematical Functions
Designing a Program
The Problem
The Analysis
The Solution
Summary
Chapter 3: Making Decisions
The Decision-Making Process
Arithmetic Comparisons
The Basic if Statement
Extending the if Statement: if-else
Using Blocks of Code in if Statements
Nested if Statements
Testing Characters
Logical Operators
The Conditional Operator
Operator Precedence: Who Goes First?
Multiple-Choice Questions
Using else-if Statements for Multiple Choices
The switch Statement
The goto Statement
Bitwise Operators
The op= Use of Bitwise Operators
Using Bitwise Operators
Bit-Precise Integers
Modern Bit Utilities
Designing a Program
The Problem
The Analysis
The Solution
Summary
Chapter 4: Loops
How Loops Work
Introducing the Increment and Decrement Operators
The for Loop
General Form of the for Loop
More on the Increment and Decrement Operators
The Increment Operator
The Pre ix and Post ix Forms of the Increment Operator
The Decrement Operator
The for Loop Revisited
Modifying the for Loop Control Variable
A for Loop with No Parameters
The break Statement in a Loop
Limiting Input Using a for Loop
Generating Pseudo-random Integers
More for Loop Control Options
Floating-Point Loop Control Variables
Chars loop Control Variables
The while Loop
Nested Loops
Nested Loops and the goto Statement
The do-while Loop
The continue Statement
Designing a Program
The Problem
The Analysis
The Solution
Summary
Chapter 5: Arrays
An Introduction to Arrays
Programming Without Arrays
What Is an Array?
Using an Array
The Address of Operator
Arrays and Addresses
Initializing an Array
Compound Literal
Finding the Size of an Array
Multidimensional Arrays
Initializing Multidimensional Arrays
Constant Arrays
Variable-Length Arrays
Designing a Program
The Problem
The Analysis
The Solution
Summary
Chapter 6: Applications with Strings and Text
What Is a String?
Variables That Store Strings
Arrays of Strings
Operations with Strings
Checking for C11/C23 Support
Finding the Length of a String
Copying Strings
Concatenating Strings
Comparing Strings
Searching a String
Tokenizing a String
Reading Newline Characters into a String
Analyzing and Transforming Strings
Converting Character Case
Converting Strings to Numerical Values
Designing a Program
The Problem
The Analysis
The Solution
Summary
Chapter 7: Pointers
A First Look at Pointers
Declaring Pointers
Accessing a Value Through a Pointer
Using Pointers
Testing for a NULL Pointer
Pointers to Constants
Constant Pointers
Naming Pointers
Arrays and Pointers
Multidimensional Arrays
Multidimensional Arrays and Pointers
Accessing Array Elements
Using Memory As You Go
Dynamic Memory Allocation: The malloc() Function
Releasing Dynamically Allocated Memory
Memory Allocation with the calloc() Function
Extending Dynamically Allocated Memory
Handling Strings Using Pointers
Using Arrays of Pointers
Pointers and Array Notation
Designing a Program
The Problem
The Analysis
The Solution
The Complete Program
Summary
Chapter 8: Structuring Your Programs
Program Structure
Variable Scope and Lifetime
Variable Scope and Functions
Storage classes
Functions
De ining a Function
The return Statement
The Pass-by-Value Mechanism
Function Prototypes
Pointers As Parameters and Return Types
const Parameters
Perils of Returning Pointers
Summary
Chapter 9: More on Functions
Pointers to Functions
Declaring a Pointer to a Function
Calling a Function Through a Function Pointer
Arrays of Pointers to Functions
Pointers to Functions As Arguments
Variables in Functions
Static Variables: Keeping Track Within a Function
Sharing Variables Between Functions
Functions That Call Themselves: Recursion
Functions with a Variable Number of Arguments
Copying a va_list
Basic Rules for Variable-Length Argument Lists
The main( ) Function
Terminating a Program
The abort() Function
The exit() and atexit() Functions
The _Exit() Function
The quick_exit() and at_quick_exit() Functions
Enhancing Performance
Declaring Functions Inline
Using the restrict Keyword
The _ Noreturn Function Speci ier
Attributes
Designing a Program
The Problem
The Analysis
The Solution
Summary
Chapter 10: Essential Input and Output
Input and Output Streams
Standard Streams
Input from the Keyboard
Formatted Keyboard Input
Input Format Control Strings
Characters in the Input Format String
Variations on Floating-Point Input
Reading Hexadecimal and Octal Values
Reading Characters Using scanf_s()
String Input from the Keyboard
Single-Character Keyboard Input
Output to the Screen
Formatted Output Using printf_s()
Escape Sequences
Integer Output
Outputting Floating-Point Values
Character Output
Other Output Functions
Unformatted Output to the Screen
Formatted Output to an Array
Formatted Input from an Array
Summary
Chapter 11: Structuring Data
Data Structures: Using struct
De ining Structure Types and Structure Variables
Accessing Structure Members
Unnamed Structures
Arrays of Structures
Structure Members in Expressions
Pointers to Structures
Dynamic Memory Allocation for Structures
More on Structure Members
Structures As Members of a Structure
Declaring a Structure Within a Structure
Pointers to Structures As Structure Members
Doubly Linked Lists
Bit Fields in a Structure
Structures and Functions
Structures As Arguments to Functions
Pointers to Structures As Function Arguments
Structure As a Function Return Value
Binary Trees
Sharing Memory
Designing a Program
The Problem
The Analysis
The Solution
Summary
Chapter 12: Working with Files
The Concept of a File
Positions in a File
File Streams
Accessing Files
Opening a File
Buffering File Operations
Renaming a File
Closing a File
Deleting a File
Writing a Text File
Reading a Text File
Reading and Writing Strings to a Text File
Formatted File Input and Output
Formatted Output to a File
Formatted Input from a File
Dealing with Errors
More Open Modes for Text Files
The freopen_s( ) Function
Binary File Input and Output
Opening a File in Binary Mode
Writing a Binary File
Reading a Binary File
Moving Around in a File
File Positioning Operations
Finding Out Where You Are
Setting a Position in a File
Using Temporary Work Files
Creating a Temporary Work File
Creating a Unique File Name
Updating Binary Files
Changing the Contents of a File
Creating a Record from Keyboard Input
Writing a Record to a File
Reading a Record from a File
Writing a File
Listing the File Contents
Updating the Existing File Contents
File Open Mode Summary
Designing a Program
The Problem
The Analysis
The Solution
Summary
Chapter 13: The Preprocessor and Debugging
Preprocessing
Including Header Files
De ining Your Own Header Files
Managing Multiple Source Files
External Variables
Static Functions
Substitutions in Your Program Source Code
Macros
Macros That Look Like Functions
Strings As Macro Arguments
Joining Two Arguments in a Macro Expansion
Preprocessor Directives on Multiple Lines
Logical Preprocessor Directives
Conditional Compilation
Testing for Multiple Conditions
Unde ining Identi iers
Testing for Speci ic Values for Identi iers
Multiple-Choice Selections
Standard Preprocessing Macros
_ Generic Macro
The Unreachable Macro
Debugging Methods
Integrated Debuggers
The Preprocessor in Debugging Assertions
Date and Time Functions
Getting Time Values
Getting the Date
Getting the Day for a Date
Summary
Chapter 14: Advanced and Specialized Topics
Working with International Character Sets
Understanding Unicode
Setting the Locale
The Wide Character Type wchar_t
Operations on Wide Character Strings
File Stream Operations with Wide Characters
Fixed Size Types That Store Unicode Characters
Specialized Integer Types for Portability
Fixed-Width Integer Types
Minimum-Width Integer Types
Maximum-Width Integer Types
The Complex Number Types
Complex Number Basics
Complex Types and Operations
Programming with Threads
Creating a Thread
Exiting a Thread
Joining One Thread to Another
Suspending a Thread
Managing Thread Access to Data
Summary
Appendix A: Computer Arithmetic
Appendix B: ASCII Character Code De initions
Appendix C: Reserved Words in C
Appendix D: Input and Output Format Speci ications
Appendix E: Standard Library Header Files
Index
About the Authors
German Gonzalez-Morris is a polyglot software architect/engineer with 20+ years in the ield, with knowledge in Java, SpringBoot, C/C++, Julia, Python, Haskell, and JavaScript, among others. He works for cloud (architecture), web-distributed applications, and microservices. German loves math puzzles (including reading Knuth, proud of solving some of Don’s puzzles), swimming, and table tennis. Also, he has reviewed several books, including those on application containers (WebLogic) and languages (C, Java, Spring, Python, Haskell, TypeScript, WebAssembly, Math for coders, regexp, Julia, data structures, and algorithms). You can see details on his blog (https://devwebcl.blogspot.com/) or X/Twitter account (@devwebcl)
Ivor Horton is self-employed in consultancy and writes programming tutorials. He worked for IBM for many years and holds a bachelor’s degree, with honors, in mathematics. Ivor’s experience at IBM includes programming in most languages (such as assembler and high-level languages on a variety of machines), real-time programming, and designing and implementing real-time closed-loop industrial control systems. He has extensive experience teaching programming to engineers and scientists (Fortran, PL/1, APL, etc.). Ivor is an expert in mechanical, process, and electronic CAD systems; mechanical CAM systems; and DNC/CNC systems.
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