Book Image

Learn C Programming

By : Jeff Szuhay
Book Image

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.
Table of Contents (33 chapters)
Section 1: C Fundamentals
Section 2: Complex Data Types
Section 3: Memory Manipulation
Section 4: Input and Output
Section 5: Building Blocks for Larger Programs

Differentiating between the NULL pointer and void*

A pointer variable should always have an assigned value. Its value should never be unknown. However, there are times when a proper address cannot be assigned or the desired address is currently unknown. For these instances, there is a constant NULLpointer. This value is defined in stddef.h and represents a value of 0. It is defined as follows:

#define NULL ((void*)0)

Here, (void*) specifies a pointer to the voidtype. Thevoidtype represents no type—a type that is unknown or a non-existent value. You cannot assign a variable to have the voidtype, but a function can returnvoid(nothing). As we have already seen, functions with thevoidreturn type don't return anything.