C# in Depth

26 CHAPTER 1 The changing face of C# developmentit utilizes. The amount of code in the library is much larger than that of the runtime,in the same way that there’s much more to a car than the engine.The .NET libraries are partially standardized. Partition IV of the CLI specificationprovides a number of different profiles (compact and kernel) and libraries. Partition IVcomes in two parts—a general textual description of the libraries, including whichlibraries are required within which profiles, and another part containing the details ofthe libraries themselves in XML format. This is the same form of documentation producedwhen you use XML comments within C#.There is much within .NET that is not within the base libraries. If you write a programthat only uses libraries from the specification, and only uses them correctly, youshould find your code works flawlessly on any implementation—Mono, .NET, or anythingelse. In practice, almost any program of any size will use libraries that aren’tstandardized—Windows Forms or ASP.NET, for instance. The Mono project has itsown libraries that are not part of .NET as well, of course, such as GTK#, in addition toimplementing many of the nonstandardized libraries.The term .NET refers to the combination of the runtime and libraries provided byMicrosoft, and it also includes compilers for C# and VB.NET. It can be seen as a wholedevelopment platform built on top of Windows.Now that we know what term means what, we can look at different versions availableof each. The subject of the version numbers chosen by Microsoft and what’s inwhich version is a slightly convoluted one, but it’s important that we all agree on whatwe mean when we talk about a particular version.1.3.2 Untangling version number chaosA newcomer to the industry might think that coming up with version numbers wouldbe easy. You start with 1, then move on to 2, then 3 in a logical progression, right? If onlythat were the case… Software products and projects of all natures like to keep minorversion changes distinct from major ones, and then there are patch levels, service packs,build numbers, and so forth. In addition, there are the codenames, which are widely usedand then abandoned, much to the frustration of “bleeding edge” book authors andpublishers. Fortunately from the point of view of C# as a language we can make life reasonablystraightforward.NOTEKeeping it simple: C# 1, C# 2, and C# 3—Throughout this book, I’ll refer toC# versions as just 1, 2, and 3. There’s little point in distinguishingbetween the two 1.x versions, and no point in adding a cumbersomeextra “.0” every time I refer to the different versions—which of course I’llbe doing quite a lot.We don’t just need to keep track of the language, unfortunately. There are five thingswe’re interested in, when it comes to versioning.■■■The .NET FrameworkFramework librariesThe CLRLicensed to Rhona Hadida