Learn C Programming

By : Jeff Szuhay

Learn C Programming

By: Jeff Szuhay

Overview of this book

C is a powerful general-purpose programming language that is excellent for beginners to learn. This book will introduce you to computer programming and software development using C. If you're an experienced developer, this book will help you to become familiar with the C programming language. This C programming book takes you through basic programming concepts and shows you how to implement them in C. Throughout the book, you'll create and run programs that make use of one or more C concepts, such as program structure with functions, data types, and conditional statements. You'll also see how to use looping and iteration, arrays, pointers, and strings. As you make progress, you'll cover code documentation, testing and validation methods, basic input/output, and how to write complete programs in C. By the end of the book, you'll have developed basic programming skills in C, that you can apply to other programming languages and will develop a solid foundation for you to advance as a programmer.

Preface

Who this book is for

What this book covers

To get the most out of this book

Download the example code files

Download the color images

Conventions used

Get in touch

Reviews

Section 1: C Fundamentals

Free Chapter

Running Hello, World!

Technical requirements

Writing your first C program

Hello, world!

Understanding the program development cycle

Edit

Compile

Many C compilers for every OS

A note about IDEs

Installing a compiler on Linux, macOS, or Windows

Run

Verify

Repeat

A note about debugging

Creating, typing, and saving your first C program

Compiling your first C program

Running your first C program

Writing comments to clarify the program later

Some guidelines on commenting code

Adding comments to the Hello, world! program

Learning to experiment with code

Summary

Understanding Program Structure

Technical requirements

Introducing statements and blocks

Experimenting with statements and blocks

Understanding delimiters

Understanding whitespace

Introducing statements

Introducing functions

Understanding function definitions

Exploring function identifiers

Exploring the function block

Exploring function return values

Passing in values with function parameters

Order of execution

Understanding function declarations

Summary

Working with Basic Data Types

Technical requirements

Understanding data types

Bytes and chunks of data

Representing whole numbers

Representing positive and negative whole numbers

Specifying different sizes of integers

Representing numbers with decimals

Representing single characters

Representing Boolean true/false

Understanding the sizes of data types

The sizeof() operator

Ranges of values

Summary

Using Variables and Assignment

Technical requirements

Understanding types and values

Introducing variables

Naming variables

Introducing explicit types of variables

Using explicit typing with initialization

Exploring constants

Literal constants

Defined values

Explicitly typed constants

Naming constant variables

Using types and assignment

Using explicit assignment, the simplest statement

Assigning values by passing function parameters

Assignment by the function return value

Summary

Exploring Operators and Expressions

Technical requirements

Expressions and operations

Introducing operations on numbers

Considering the special issues resulting from operations on numbers

Understanding NaN

Understanding underflow NaN

Understanding overflow NaN

Considering precision

Exploring type conversion

Understanding implicit type conversion and values

Using explicit type conversion – casting

Introducing operations on characters

Exploring logical and relational operators

Bitwise operators

The conditional operator

The sequence operator

Compound assignment operators

Multiple assignments in a single expression

Incremental operators

Postfix versus prefix incrementation

Order of operations and grouping

Summary

Exploring Conditional Program Flow

Technical requirements

Understanding conditional expressions

Introducing the if()… else… complex statement

Using a switch()… complex statement

Introducing multiple if()… statements

Using nested if()… else… statements

The dangling else… problem

Summary

Exploring Loops and Iteration

Technical requirements

Understanding repetition

Understanding brute-force repetition

Introducing the while()… statement

Introducing the for()… statement

Introducing the do … while() statement

Understanding loop equivalency

Understanding unconditional branching – the dos and (mostly) don'ts of goto

Further controlling loops with break and continue

Understanding infinite loops

Summary

Creating and Using Enumerations

Technical requirements

Introducing enumerations

Defining enumerations

Using enumerations

The switch()… statement revisited

Summary

Section 2: Complex Data Types

Creating and Using Structures

Technical requirements

Understanding structures

Declaring structures

Initializing structures and accessing structure elements

Performing operations on structures – functions

Structures of structures

Initializing structures with functions

Printing a structure of structures – reusing functions

The stepping stone to object-oriented programming

Summary

Creating Custom Data Types with typedef

Technical requirements

Renaming intrinsic types with typedef

Using synonyms

Simplifying the use of enum types with typedef

Simplifying the use of struct types with typedef

Other uses of typedef

Some more useful compiler options

Using a header file for custom types and the typedef specifiers

Summary

Working with Arrays

Technical requirements

Declaring and initializing arrays

Initializing arrays

Accessing array elements

Assigning values to array elements

Operating on arrays with loops

Using functions that operate on arrays

Summary

Working with Multi-Dimensional Arrays

Technical requirements

Going beyond one-dimensional arrays to multi-dimensional arrays

Revisiting one-dimensional arrays

Moving on to two-dimensional arrays

Moving on to three-dimensional arrays

Considering N-dimensional arrays

Declaring and initializing multi-dimensional arrays

Declaring arrays of two dimensions

Initializing arrays of two dimensions

Declaring arrays of three dimensions

Initializing arrays of three dimensions

Declaring and initializing arrays of N dimensions

Accessing elements of multi-dimensional arrays

Manipulating multi-dimensional arrays – loops within loops

Using nested loops to traverse a two-dimensional array

Using nested loops to traverse a three-dimensional array

Using multi-dimensional arrays in functions

Summary

Using Pointers

Technical requirements

Addressing pointers – the boogeyman of C programming

Why use pointers at all?

Introducing pointers

Understanding direct addressing and indirect addressing

Understanding memory and memory addressing

Managing and accessing memory

Exploring some analogies in the real world

Declaring the pointer type, naming pointers, and assigning addresses

Declaring the pointer type

Naming pointers

Assigning pointer values (addresses)

Operations with pointers

Assigning pointer values

Differentiating between the NULL pointer and void*

Understanding the void* type

Accessing pointer targets

Pointer arithmetic

Comparing pointers

Verbalizing pointer operations

Variable function arguments

Passing values by reference

Passing addresses to functions without pointer variables

Pointers to pointers

Using pointers to structures

Accessing structures and their elements via pointers

Using pointers to structures in functions

Summary

Understanding Arrays and Pointers

Technical requirements

Understanding array names and pointers

Understanding array elements and pointers

Accessing array elements via pointers

Operations on arrays using pointers

Using pointer arithmetic

Using the increment operator

Passing arrays as function pointers revisited

Interchangeability of array names and pointers

Introducing an array of pointers to arrays

Summary

Working with Strings

Technical requirements

Characters – the building blocks of strings

The char type and ASCII

Beyond ASCII – UTF-8 and Unicode

Operations on characters

Getting information about characters

Manipulating characters

Exploring C strings

An array with a terminator

Strengths of C strings

Weaknesses of C strings

Declaring and initializing a string

String declarations

Initializing strings

Passing a string to a function

Empty strings versus null strings

Hello, World! revisited

Creating and using an array of strings

Common operations on strings – the standard library

Common functions

Safer string operations

Summary

Creating and Using More Complex Structures

Technical requirements

Introducing the need for complex structures

Revisiting card4.h

Understanding an array of structures

Creating an array of structures

Accessing structure elements within an array

Manipulating an array of structures

Using a structure with other structures

Creating a structure consisting of other structures

Accessing structure elements within the structure

Manipulating a structure consisting of other structures

Using a structure with arrays

Understanding randomness and random number generators

Creating a structure with an array

Accessing array elements within a structure

Manipulating array elements within a structure

Revisiting the hand structure

Revisiting hand operations

Using a structure with an array of structures

Creating a structure with an array of structures

Accessing individual structure elements of the array within a structure

Manipulating a structure with an array of structures

Completing carddeck.c

Revisiting the deck structure

Revisiting deck operations

A basic card program

Summary

Section 3: Memory Manipulation

Understanding Memory Allocation and Lifetime

Technical requirements

Defining storage classes

Understanding automatic versus dynamic storage classes

Automatic storage

Dynamic storage

Understanding internal versus external storage classes

Internal or local storage classes

External or global storage classes

The lifetime of automatic storage

Exploring the static storage class

Internal static storage

External static storage

The lifetime of static storage

Summary

Using Dynamic Memory Allocation

Technical requirements

Introducing dynamic memory

A brief tour of C's memory layout

Allocating and releasing dynamic memory

Allocating dynamic memory

Releasing dynamic memory

Accessing dynamic memory

The lifetime of dynamic memory

Special considerations for dynamic allocation

Heap memory management

Memory leaks

The linked list dynamic data structure

Linked list structures

Declaring operations on a linked list

Pointers to functions

More complex operations on a linked list

A program to test our linked list structure

Other dynamic data structures

Summary

Section 4: Input and Output

Exploring Formatted Output

Technical requirements

Revisiting printf()

Understanding the general format specifier form

Using format specifiers for unsigned integers

Using unsigned integers in different bases

Considering negative numbers as unsigned integers

Exploring powers of 2 and 9 in different bases

Printing pointer values

Using format specifiers for signed integers

Using the signed integer field width, precision, alignment, and zero-filling

Formatting long-long integers

Powers of 2 and 9 with different modifiers

Using format specifiers for floats and doubles

Using the floating-point field width, precision, alignment, and zero-filling

Printing doubles in hexadecimal format

Printing optimal field widths for doubles

Using format specifiers for strings and characters

Using the string field width, precision, alignment, and zero-filling

Exploring the sub-string output

Using single character formatting

Summary

Getting Input from the Command Line

Technical requirements

Revisiting the main() function

The special features of main()

The two forms of main()

Using argc and argv

A simple use of argc and argv

Command-line switches and command-line processors

Summary

Exploring Formatted Input

Technical requirements

Introducing streams

Understanding the standard output stream

Understanding the standard input stream

Revisiting the console output with printf() and fprintf()

Exploring the console input with scanf()

Reading formatted input with scanf()

Reading numerical input with scanf()

Reading string and character input with scanf()

Using a scan set to limit possible input characters

Controlling the scanf() input field width

Using internal data conversion

Using sscanf() and sprintf() to convert values into and from strings

Converting strings into numbers with atoi() and atod()

Exploring unformatted input and output

Getting the string input and output to/from the console

Using the simple input and output of strings with gets() and puts()

Understanding why using gets() could be dangerous

Creating a sorted list of names with fgets() and fputs()

Summary

Working with Files

Technical requirements

Understanding basic file concepts

Revisiting file streams

Understanding the properties of the FILE streams

Opening and closing a file

Understanding file operations for each type of stream

Introducing the filesystem essentials

Introducing the filesystem

Understanding a file path

Understanding a filename

Opening files for reading and writing

Getting filenames from within the program

Getting filenames from the command line

Summary

Using File Input and File Output

Technical requirements

File processing

Creating a template program to process filenames given on the command line

Creating a file of unsorted names

Trimming the input string from fgets()

Reading names and writing names

Reading unsorted names and sorting them for output

Using a linked list to sort names

Writing names in sorted order

Summary

Section 5: Building Blocks for Larger Programs

Working with Multi-File Programs

Technical requirements

Understanding multi-file programs

Using header files for declarations and source files for definitions

Creating source files

Creating header files

Revisiting the preprocessor

Understanding the limits and dangers of the preprocessor

Knowing some dangers of the preprocessor

Using the preprocessor effectively

Debugging with the preprocessor

Creating a multi-file program

Extracting Card structures and functions

Extracting Hand structures and functions

Extracting Deck structures and functions

Finishing the dealer.c program

Building a multi-file program

Summary

Understanding Scope

Technical requirements

Defining scope – visibility, extent, and linkage

Exploring visibility

Exploring extent

Exploring linkage

Understanding compilation units

Putting visibility, extent, and linkage all together

Exploring variable scope

Understanding the block scope of variables

Understanding function parameter scope

Understanding file scope

Understanding global scope

Understanding function scope

Understanding scope and information hiding

Using the static specifier for functions

Summary

Epilog

Taking the next steps

To get the most out of this book

To use this book, you will need a basic text editor, a terminal or console application, and a compiler. Descriptions of each of these and how to download and use them are provided in Chapter 1, Running Hello, World!. Here are the technical requirements for this book:

Operating System			Cost	Download URL
Linux/Unix
	Text Editor(choose one)
		Nano	Free	https://www.nano-editor.org/download.php
		Vim or vi	<Built-in>	N/A
		GEdit	<Built-in>	https://wiki.gnome.org/Apps/Gedit
		Emacs	Free	https://www.gnu.org/software/emacs/download.html
	Compiler			(Installation based on version of Linux/Unix)
		GCC	<Built-in>	https://gcc.gnu.org/install/ (see the notes following this table for certain Linux versions)
	Terminal
		Terminal	<Built-in>	N/A
macOS
	Text Editor(choose one)
		Vim or vi	<Built-in>	N/A
		emacs	Free	https://www.gnu.org/software/emacs/download.html
		Bbedit	Free	https://www.barebones.com/products/bbedit/
	Compiler
		Clang	<Built-in>
	Terminal
		terminal.app	<Built-in>	N/A
Windows
	Text Editor(choose one)
		Notepad	<Built-in>	N/A
		Notepad++	Free	https://notepad-plus-plus.org/downloads/
		emacs	Free	https://www.gnu.org/software/emacs/download.html
	Compiler
		Cygwin	Free	http://www.cygwin.com
		MinGW	Free	http://mingw-w64.org
	Terminal
		Console	<Built-in>	N/A

To install GCC on certain Linux OSes, follow these steps:

If you are running an RPM-based Linux, such as RedHat, Fedora, or CentOS, on the command line in Terminal, enter the following:

$ sudo yum group install development-tools

If you are running Debian Linux, on the command line in Terminal, enter the following:

$ sudo apt-get install build-essential

To verify your installation of GCC or Clang for any platform, on the command line in the Terminal, enter the following:

$ cc --version

Whichever version of this book you are using, digital or hard copy, we advise you to type the code yourself. After you do that, you can access the code via the GitHub repository (link available in the next section). Doing so will help you avoid any potential errors related tothe copying and pasting of code.

If you are an absolute beginner, once you have the necessary development tools, you will need to learn how to read a programming book. If you have taken an algebra course or a calculus course in school, then you will need to approach learning from a programming book in a similar fashion:

Read through the chapter to get an overview of the concepts being presented.
Begin the chapter again, this time typing in each program as you encounter it. Make sure you get the expected output before moving on. If you don't get the expected output, try to figure out what is different in your program from the one given. Learning to program is a lot like learning math—youmustdo the exercises and get the programs to work. You cannot learn to program just by looking at programs; to learn to program, you must program. There is no way around that.
Focus upon memorizing keywords and syntax. This will greatly speed up your learning time.

Be aware that you will need to sharpen the precision of your thinking. Computer language syntax is extremely precise and you will need to pay extra attention to it. You will also have to think much more precisely and in sometimes excruciating detail about the steps needed to solve a particular problem.
Review both the concepts and example programs. Make a note of anything you don't understand.

If you are an experienced programmer who is new to C, I still strongly advise you to first skim the text and examples. Then, enter the programs and get them to work on your system. This will help you to learn C syntax and its idioms more quickly.

I have found that it is important to understand what kind of book you are reading so that you can use it in the most appropriate way. There are several kinds of computer programming books:

Conceptual books, which deal with the underlying ideas and motivation for the topics they present. Kernighan and Ritchie'sThe C Programming Languageis one such book.
Textbooksthat go through every major area of the language, sometimes in gory detail and usually with a lot of code snippets. Deitel and Deitel's books, as well asC Programming: A Modern Approach, by K. N. King, are examples of these. They are often best used in a formal programming course.
Reference books,which describe the specifics of each syntax element.C: A Reference Manual, by Harbison and Steele, is one such book.
Cookbooks, which present specific solutions to specific problems in a given language.Advanced C Programming by Example, by Perry, Expert C Programming: Deep Secrets, by Van Der Linden, andAlgorithms in C, by Sedgewick, are examples of these.
Topical books, which delve deeply into one or more aspects of a programing language.Pointers in C, by Reek, is one example.
Practice books, which deal with how to address programming with C generally.C Interfaces and Implementations, by Hanson, and21st Century C: C Tips from the New School, by Klemens, are two examples of these.

There are different ways to use these books. For instance, read a conceptual book once, but keep a reference book around and use it often. Try to find cookbooks that offer the kinds of programs you are likely to need and use them as needed.

I think of this book as a combination of a C cookbook, a C reference book, and a C practice book. All of the programs are working examples that can be used to verify how your compiler behaves on your system. Enough of the C language has been included that it may also be used as afirst approximationreference. Throughout, my intent has been to show good programming practice with C.

I would expect that Learn C Programmingwill not be your last book on C. When you consider other C books, be sure that they pertain to C99 at a minimum; ideally, they should include C11 or C18. Most C code before C99 is definitely old school; more effective programming practices and methods have been developed since before C99.

Learn C Programming

By : Jeff Szuhay

Learn C Programming

By: Jeff Szuhay

Overview of this book

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Learn C Programming

To get the most out of this book