Datasheet

Part I: The C# Language

In addition, the preceding definition of the .NET Framework includes no restriction on the type of

applications that are possible. That ’ s because there is no restriction — the .NET Framework allows the

creation of Windows applications, Web applications, Web services, and pretty much anything else you

can think of.

The .NET Framework has been designed so that it can be used from any language, including C# (the

subject of this book) as well as C++, Visual Basic, JScript, and even older languages such as COBOL. For

this to work, .NET - specific versions of these languages have also appeared, and more are being released

all the time. Not only do all of these have access to the .NET Framework, but they can also communicate

with each other. It is perfectly possible for C# developers to make use of code written by Visual Basic

programmers, and vice versa.

All of this provides a hitherto unthinkable level of versatility and is part of what makes using the .NET

Framework such an attractive prospect.

What ’ s in the .NET Framework?

The .NET Framework consists primarily of a gigantic library of code that you use from your client

languages (such as C#) using object - oriented programming (OOP) techniques. This library is categorized

into different modules — you use portions of it depending on the results you want to achieve. For

example, one module contains the building blocks for Windows applications, another for network

programming, and another for Web development. Some modules are divided into more specific

submodules, such as a module for building Web services within the module for Web development.

The intention is for different operating systems to support some or all of these modules, depending on

their characteristics. A PDA, for example, would include support for all the core .NET functionality, but

is unlikely to require some of the more esoteric modules.

Part of the .NET Framework library defines some basic types . A type is a representation of data, and

specifying some of the most fundamental of these (such as “ a 32 - bit signed integer ” ) facilitates

interoperability between languages using the .NET Framework. This is called the Common Type

System (CTS) .

As well as supplying this library, the .NET Framework also includes the .NET Common Language Runtime

(CLR) , which is responsible for maintaining the execution of all applications developed using the .NET

library.

Writing Applications Using the .NET Framework

Writing an application using the .NET Framework means writing code (using any of the languages that

support the Framework) using the .NET code library. In this book you use VS and VCE for your

development — VS is a powerful, integrated development environment that supports C# (as well as

managed and unmanaged C++, Visual Basic, and some others). VCE is a slimmed down (and free)

version of VS that supports C# only. The advantage of these environments is the ease with which .NET

features can be integrated into your code. The code that you create will be entirely C# but will use the

.NET Framework throughout, and you ’ ll make use of the additional tools in VS and VCE where

necessary.

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