INTRODUCTION

THE C# LANGUAGE WAS UNVEILED TO THE WORLD when Microsoft announced the first version of its .NET Framework in 2002. Since then, its popularity has rocketed, and it has arguably become the language of choice for desktop, web, cloud, and cross-platform developers who use .NET. Part of the appeal of C# comes from its clear syntax, which derives from C/C++ but simplifies some things that have previously discouraged some programmers. Despite this simplification, C# has retained the power of C++, and there is no reason now not to move into C#. The language is not difficult, and it is a great one with which to learn elementary programming techniques. This ease of learning combined with the capabilities of the .NET Framework make C# an excellent way to start your programming career.

The latest release of C# is C# 9 (included with.NET 5.0 and .NET Framework 4.8), which builds on the existing successes and adds even more attractive features. The latest releases of both Visual Studio and Visual Studio Code line of development tools also bring many tweaks and improvements to make your life easier and to dramatically increase your productivity.

This book is intended to teach you about all aspects of C# programming, including the language itself, desktop, cloud, and cross-platform programming, making use of data sources, and some new and advanced techniques. You will also learn about the capabilities of Visual Studio and all the ways that this product can aid your application development.

The book is written in a friendly, mentor-style fashion, with each chapter building on previous ones, and every effort is made to ease you into advanced techniques painlessly. At no point will technical terms appear from nowhere to discourage you from continuing; every concept is introduced and discussed as required. Technical jargon is kept to a minimum, but where it is necessary, it, too, is properly defined and laid out in context.

The authors of this book are both experts in their field and are enthusiastic in their passion for the C# language and .NET. Nowhere will you find two people better qualified to take you under their collective wing and nurture your understanding of C# from first principles to advanced techniques. Along with the fundamental knowledge it provides, this book is packed full of helpful hints, tips, exercises, and full-fledged example code (available for download on this book's web page at www.wiley.com and at github.com/benperk/BeginningCSharpAndDotNET) that you will find yourself returning to repeatedly as your career progresses.

We pass this knowledge on without begrudging it and hope that you will be able to use it to become the best programmer you can be. Good luck, and all the best!

WHO THIS BOOK IS FOR

This book is for everyone who wants to learn how to program in C# using .NET. It is for absolute beginners who want to give programming a try by learning a clean, modern, elegant programming language. But it is also for people familiar with other programming languages who want to explore the .NET platform, as well as for existing .NET developers who want to give Microsoft's .NET flagship language a try.

WHAT THIS BOOK COVERS

The early chapters cover the language itself, assuming no prior programming experience. If you have programmed in other languages before, much of the material in these chapters will be familiar. Many aspects of C# syntax are shared by other languages, and many structures are common to practically all programming languages (such as looping and branching structures). However, even if you are an experienced programmer, you will benefit from looking through these chapters to learn the specifics of how these techniques apply to C#.

If you are new to programming, you should start from the beginning, where you will learn basic programming concepts and become acquainted with both C# and the .NET platform that underpins it. If you are new to .NET but know how to program, you should read Chapter 1 and then skim through the next few chapters before continuing with the application of the C# language. If you know how to program but have not encountered an object-oriented programming language before, you should read the chapters from Chapter 8 onward.

Alternatively, if you already know the C# language, you might want to concentrate on the chapters dealing with the most recent .NET and C# language developments, specifically the chapters on collections, generics, and C# language enhancements (Chapters 11 and 12).

The chapters in this book have been written with a dual purpose in mind: They can be read sequentially to provide a complete tutorial in the C# language, and they can be dipped into as required for reference material.

In addition to the core material, starting with Chapter 3 most chapters also include a selection of exercises at the end, which you can work through to ensure that you have understood the material. The exercises range from simple multiple choice or true/false questions to more complex exercises that require you to modify or build applications. The answers to all the exercises are provided in the Appendix. You can also find these exercises as part of the wiley.com code downloads on this book's page at www.wiley.com.

Every chapter receives an overhaul with every new release of C# and .NET, the less relevant material is removed, and new material added. All the code has been tested against the latest version of the development tools used, and all the screenshots have been retaken in the most current version of the Windows OS to provide the most current windows and dialog boxes. New highlights of this edition include the following:

• Additional and improved code examples for you to try out
• Examples of programming ASP.NET Core for running cross-platform
• Examples of programming cloud applications, using Azure SDK to create and access cloud resources

HOW THIS BOOK IS STRUCTURED

This book is divided into four sections:

• Introduction-Purpose and general outline of the book's contents
• The C# Language-Covers all aspects of the C# language, from the fundamentals to object-oriented techniques
• Data Access-How to use data in your applications, including data stored in files on your hard disk, data stored in XML format, and data in databases
• Additional Techniques-An examination of some extra ways to use C# and .NET, including cloud and cross-platform development, ASP.NET Web API, Windows Presentation Foundation (WPF), Windows Communication Foundation (WCF), and Universal Windows Applications

The following sections describe the chapters in the three major parts of this book.

The C# Language (Chapters 1-13)

Chapter 1 introduces you to C# and how it fits into the .NET landscape. You will learn the fundamentals of programming in this environment and how Visual Studio (VS) fits in.

Chapter 2 starts you off with writing C# applications. You will look at the syntax of C# and put the language to use with sample command-line and Windows applications. These examples demonstrate just how quick and easy it can be to get up and running, and along the way you will be introduced to the Visual Studio development environment and the basic windows and tools that you'll be using throughout the book.

Next, you will learn more about the basics of the C# language. You will learn what variables are and how to manipulate them in Chapter 3. You will enhance the structure of your applications with flow control (looping and branching) in Chapter 4, and you will see some more advanced variable types such as arrays in Chapter 5. In Chapter 6 you will start to encapsulate your code in the form of functions, which makes it much easier to perform repetitive operations and makes your code much more readable.

By the beginning of Chapter 7 you will have a handle on the fundamentals of the C# language, and you will focus on debugging your applications. This involves looking at outputting trace information as your applications are executed, and at how Visual Studio can be used to trap errors and lead you to solutions for them with its powerful debugging environment.

From Chapter 8 onward you will learn about object-oriented programming (OOP), starting with a look at what this term means and an answer to the eternal question, "What is an object?" OOP can seem quite difficult at first. The whole of Chapter 8 is devoted to demystifying OOP and explaining what makes it so great, and you will not actually deal with much C# code until the very end of the chapter.

Everything changes in Chapter 9, when you put theory into practice and start using OOP in your C# applications. This is where the true power of C# lies. You will start by looking at how to define classes and interfaces, and then move on to class members (including fields, properties, and methods) in Chapter 10. At the end of that chapter, you will start to assemble a card game application, which is developed over several chapters and will help to illustrate OOP.

Once you have learned how OOP works in C#, Chapter 11 moves on to look at common OOP scenarios, including dealing with collections of objects, and comparing and converting objects. Chapter 12 looks at a useful feature of C# that was...