Programming C# 5.0: Building Windows 8, Web, and Desktop Applications for the .NET 4.5 Framework

1107 Pages·2012·8.33 MB·English

by  Ian Griffiths

Programming C# 5.0
Ian Griffiths
Published by O’Reilly Media
Beijing ⋅ Cambridge ⋅ Farnham ⋅ Köln ⋅ Sebastopol ⋅ Tokyo
I dedicate this book to my excellent wife Deborah, and to my wonderful daughter, Hazel, who arrived while
this book was a work in progress.
Preface
C# is now well into its second decade. It has grown steadily in both power and
size, but Microsoft has always kept the essential characteristics intact—C# still
feels like the same language as was first unveiled back in 2000. Each new
capability is designed to integrate cleanly with the rest, enhancing the language
without turning it into an incoherent bag of miscellaneous features. This
philosophy is evident in the most important new addition to C#—its support for
asynchronous programming. It has always been possible to use asynchronous APIs
in C#, but in the past, this tended to involve convoluted code. In C# 5.0, you can
write asynchronous code that looks almost exactly like normal code, so instead of
adding weight to the language, this new asynchronous programming support makes
things simpler.
Even though C# continues to be a fairly straightforward language at its heart, there
is a great deal more to say about it now than in its first incarnation. Successive
editions of this book have responded to the language’s progress with ever-
increasing page counts, but this latest edition does not merely try to cram in yet
more details. It expects a somewhat higher level of technical ability from its readers
than before.
Who This Book Is For
I have written this book for experienced developers—I’ve been programming for
years, and I’ve set out to make this the book I would want to read if that experience
had been in other languages, and I were learning C# today. Whereas previous
editions explained some basic concepts such as classes, polymorphism, and
collections, I am assuming that readers will already know what these are. The early
chapters still describe how C# presents these common ideas, but the focus is on the
details specific to C#, rather than the broad concepts. So if you have read previous
editions of this book, you will find that this one spends less time on these basic
concepts, and goes into rather more detail on everything else.
Conventions Used in This Book
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Using Code Examples
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Acknowledgments
Many thanks to the book’s official technical reviewers: Glyn Griffiths, Alex Turner,
and Chander Dhall. I’d also like to give a big thank you to those who reviewed
individual chapters, or otherwise offered help or information that improved this
book: Brian Rasmussen, Eric Lippert, Andrew Kennedy, Daniel Sinclair, Brian
Randell, Mike Woodring, Mike Taulty, Mary Jo Foley, Bart De Smet, and Stephen
Toub.
Thank you to everyone at O’Reilly whose work brought this book into existence. In
particular, thanks to Rachel Roumeliotis for encouraging me to write this new
edition, and thank you also to Kristen Borg, Rachel Monaghan, Gretchen Giles,
and Yasmina Greco for your excellent support. Finally, thank you to John Osborn,
for taking me on as an O’Reilly author back when I wrote my first book.
Chapter 1. Introducing C#
The C# programming language (pronounced “see sharp”) can be used for many
kinds of applications, including websites, desktop applications, games, phone apps,
and command-line utilities. C# has been center stage for Windows developers for
about a decade now, so when Microsoft announced that Windows 8 would
introduce a new[1] style of application, optimized for touch-based interaction on
tablets, it was no surprise that C# was one of the four languages to offer full
support from the start for these applications (the others being C++, JavaScript, and
Visual Basic).
Although Microsoft invented C#, the language and its runtime are documented by
the standards body ECMA, enabling anyone to implement C#. This is not merely
hypothetical. The open source Mono project (http://www.mono-project.com/)
provides tools for building C# applications that run on Linux, Mac OS X, iOS, and
Android.
Why C#?
Although there are many ways you can use C#, other languages are always an
option. Why might you choose C# over them? It will depend on what you need to
do, and what you like and dislike in a programming language. I find that C#
provides considerable power and flexibility, and works at a high enough level of
abstraction that I don’t expend vast amounts of effort on little details not directly
related to the problems my programs are trying to solve. (I’m looking at you, C++.)
Much of C#’s power comes from the range of programming techniques it supports.
For example, it offers object-oriented features, generics, and functional
programming. It supports both dynamic and static typing. It provides powerful list-
and set-oriented features, thanks to Language Integrated Query (LINQ). The most
recent version of the language adds intrinsic support for asynchronous
programming.
Some of the most important benefits of using C# come from its runtime, which
provides services such as security sandboxing, runtime type checking, exception
handling, thread management, and perhaps its most important feature, automated
memory management. The runtime provides a garbage collector that frees
developers from much of the work associated with recovering memory that the
program is no longer using.
Of course, languages do not exist in a vacuum—high-quality libraries with a broad
range of features are essential. There are some elegant and academically beautiful
languages that are glorious right up until you want to do something prosaic, such as
talking to a database or determining where to store user settings. No matter how
strong a set of programming idioms a language offers, it also needs to provide full
and convenient access to the underlying platform’s services. C# is on very strong
ground here, thanks to the .NET Framework.
The .NET Framework encompasses both the runtime and the libraries that C#
programs use on Windows. The runtime part is called the Common Language
Runtime (usually abbreviated to CLR) because it supports not just C#, but any
.NET language. Numerous languages can run in .NET. Microsoft’s development
environment, Visual Studio, provides Visual Basic, F#, and .NET extensions for
C++, for example, and there are open source .NET-based implementations of
Python and Ruby (called IronPython and IronRuby, respectively). The CLR has a
Common Type System (CTS) that enables code from multiple languages to
interoperate freely, which means that .NET libraries can usually be used from any
.NET language—F# can consume libraries written in C#, C# can use Visual Basic
libraries, and so on. The .NET Framework includes an extensive class library. This
library provides wrappers for many features of the underlying operating system
(OS), but it also provides a considerable amount of functionality of its own. It
contains over 10,000 classes, each with numerous members.
NOTE
Some parts of the .NET Framework class library are specific to Windows. There are library features
dedicated to building Windows desktop applications, for example. However, other parts are more generic,
such as the HTTP client classes, which would be relevant on any operating system. The ECMA
specification for the runtime used by C# defines a set of library features that are not dependent on any
particular operating system. The .NET Framework class library supports all these features, of course, as well
as offering Microsoft-specific ones.
The libraries built into the .NET Framework are not the whole story—many other
frameworks provide their own .NET class libraries. SharePoint has an extensive