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 global scope

To make external variables in one file available to another file, we need to declare them with the extern storage class. Suppose nameSorter.c is part of a sortem.c program and sortem.c needs to access those values. This would be done with the following declaration:

#include <...>
#include "nameSorter.h"

extern const int listMax;
extern const int stringMax;


Note that sortem.c uses the same type declarations found in nameSorter.c but adds the extern keyword. The external variables are declared/allocated in nameSorter.c, and so have file scope in that file and external variable extent. Their linkage scope has been extended to sortem.c so that those variables are now visible throughout that source file. Any other file part of the sortem.c program that might need to use listMax and stringMax would simply need to add the same declaration as a part of its compilation unit.

This can be done in several ways: one is to add...