C# is a new language invented at Microsoft and introduced with Visual Studio.NET. More than a million lines of C# code already have gone into the implementation of the .NET class framework. This book covers the C# language and its use in programming the .NET class framework, illustrating application domains such as ASP.NET and XML.

My general strategy in presenting the material is to introduce a programming task and then walk through one or two implementations, introducing language features or aspects of the class framework as they prove useful. The goal is to demonstrate how to use the language and class framework to solve problems rather than simply to list language features and the class framework API.

Learning C# is a two-step process: learning the details of the C# language and then becoming familiar with the .NET class framework. This two-step process is reflected in the organization of this text.

In the first step we walk through the language--both its mechanisms, such as class and interface inheritance and delegates, and its underlying concepts, such as its unified type system, reference versus value types, boxing, and so on. This step is covered in the first four chapters.

The second step is to become familiar with the .NET class framework, in particular with Windows and Web programming and the support for XML. This is the focus of the second half of the book.

Working your way through the text should jump-start your C# programming skills. In addition, you'll become familiar with a good swatch of the .NET class framework. All the program code is available for download at my company's Web site www.objectwrite.com.

Mail can be sent to me directly at slippman@objectwrite.com.

Organization of the Book

The book is organized into eight relatively long chapters. The first four chapters focus on the C# language, looking at the built-in language features, the class mechanism, class inheritance, and interface inheritance. The second four chapters explore the various library domains supported within the .NET class framework.

Chapter 1 covers the basic language, as well as some of the fundamental classes provided within the class framework. The discussion is driven by the design of a small program. Concepts such as namespaces, exception handling, and the unified type system are introduced.

Chapter 2 covers the fundamentals of building classes. We look at access permission, distinguish between const and readonly members, and cover specialized methods such as indexers and properties. We walk through the different strategies of member initialization, as well as the rules for operator overloading and conversion operators. We look at the delegate type, which serves as a kind of universal pointer to a function.

Chapters 3 and 4 cover, in turn, class and interface inheritance. Class inheritance allows us to define a family of specialized types that override a generic interface, such as an abstract WebRequest base class and a protocol-specific HttpWebRequest subtype. Interface inheritance, on the other hand, allows us to provide a common service or shared attribute for otherwise unrelated types. For example, the IDisposable interface frees resources. Classes holding database connections or window handles are both likely to implement IDisposable, although they are otherwise unrelated.

Chapter 5 provides a wide-ranging tour of the .NET class library. We look at input and output, including file and directory manipulation, regular expressions, sockets and thread programming, the WebRequest and WebResponse class hierarchies, a brief introduction to ADO.NET and establishing database connections, and the use of XML.

Chapters 6 and 7 cover, in turn, drag-and-drop Windows Forms and Web Forms development. Chapter 7 focuses on ASP.NET, and the Web page life cycle. Both chapters provide lots of examples of using the prebuilt controls and attaching event handlers for user interaction.

The final chapter provides a programmer's introduction to the .NET Common Language Runtime. It focuses on assemblies, type reflection, and attributes, and concludes with a brief look at the underlying intermediate language that is the compilation target of all .NET languages.

Written for Programmers

The book does not assume that you know C++, Visual Basic, or Java. But it does assume that you have programmed in some language. So, for example, I don't assume that you know the exact syntax of the C# foreach loop statement, but I do assume that you know what a loop is. Although I will illustrate how to invoke a function in C#, I assume you know what I mean when I say we "invoke a function." This text does not require previous knowledge of object-oriented programming or of the earlier versions of ASP and ADO.

Some people--some very bright people--argue that under .NET, the programming language is secondary to the underlying Common Language Runtime (CLR) upon which the languages float like the continents on tectonic plates. I don't agree. Language is how we express ourselves, and the choice of one's language affects the design of our programs. The underlying assumption of this book is that C# is the preferred language for .NET programming.

The book is organized into eight relatively long chapters. The first set of four chapters focuses on the C# language, looking at the built-in language features, the class mechanism, class inheritance, and interface inheritance. The second set of four chapters explores the various library domains supported within the .NET class framework, such as regular expressions, threading, sockets, Windows Forms, ASP.NET, and the Common Language Runtime.

Lexical Conventions

Type names, objects, and keywords are set off in Courier font, as in int, a predefined language type; Console, a class defined in the framework; maxCount, an object defined either as a data member or as a local object within a function; and foreach, one of the predefined loop statements. Function names are followed by an empty pair of parentheses, as in WriteLine(). The first introduction of a concept, such as garbage collection or data encapsulation, is highlighted in italics. These conventions are intended to make the text more readable.

Resources

The richest documentation that you will be returning to time and again is the Visual Studio.NET documentation. The .NET framework reference is essential to doing any sort of C#/.NET programming.

Another rich source of information about .NET consists of the featured articles and columns in the MSDN Magazine. I'm always impressed by what I find in each issue. You can find it online at http://msdn.microsoft.com/msdnmag.

The DOTNET mailing list sponsored by DevelopMentor is a rich source of information. You can subscribe to it at http://discuss.develop.com.

Anything Jeffrey Richter, Don Box, Aaron Skonnard, or Jeff Prosise writes about .NET (or XML in Aaron's case) should be considered essential reading. Currently, most of their writing has appeared only as articles in MSDN Magazine.Here is the collection of books that I have referenced or found helpful:

• Active Server Pages+, by Richard Anderson, Alex Homer, Rob Howard, and Dave Sussman, Wrox Press, Birmingham, England, 2000.
• C# Essentials, by Ben Albahari, Peter Drayton, and Brad Merrill, O'Reilly, Cambridge, MA, 2001.
• C# Programming, by Burton Harvey, Si

Stanley B. Lippman is Architect with the Visual C++ development team at Microsoft. Previously, he served as a Distinguished Consultant at the Jet Propulsion Laboratories (JPL). Stan spent more than twelve years at Bell Laboratories, where he worked with Bjarne Stroustrup on the original C++ implementation and the Foundation research project. After Bell Laboratories, Stan worked at Disney Feature Animation, originally as principal software engineer, then as software technical director on Fantasia 2000.

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