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

Understanding why using gets() could be dangerous

There is a significant difference between gets() and fgets(). The following function prototypes for these two functions highlight their differences:

char* gets( char* str );
char* fgets( char* str , int size , FILE* stream );

From this, we see that gets() requires no limits on how many characters it reads; therefore, gets()has the potential to read an infinite amount of input. On the other hand,fgets()must be given a maximum number of characters to be read in the size parameter. fgets() will read up to size-1 characters unless EOF or <newline> are encountered.

Because there are no limits on the length of the string to gets(), it has the potential to read beyond the size of the string buffer. If this happens, in a best-case scenario, mayhem will ensue and the program will crash. In a worst-case scenario, malicious input could be devised such that the program does not crash and causes control to extend...