【正文】
onditional written in Visual Basic differs from the syntax of a conditional written in C++, the programming function is the same. Finally, most programming languages have similar variable data types. In most languages, you have some means of representing strings and integers, for example. The maximum and minimum size of an integer might depend on the language, but the basic data type is the same. Maintaining all this functionality for multiple languages requires a lot of work. Why keep reinventing the wheel? Wouldn39。t it be easier to create all this functionality once and use it for every language? The .NET Framework Class Library does exactly that. It consists of a vast set of classes designed to satisfy any conceivable programming need. For example, the .NET framework contains classes for handling database access, working with the file system, manipulating text, and generating graphics. In addition, it contains more specialized classes for performing tasks such as working with regular expressions and handling work protocols. The .NET framework, furthermore, contains classes that represent all the basic variable data types such as strings, integers, bytes, characters, and arrays. Most importantly, for purposes of this book, the .NET Framework Class Library contains classes for building pages. You need to understand, however, that you can access any of the .NET framework classes when you are building your pages. Understanding Namespaces As you might guess, the .NET framework is huge. It contains thousands of classes (over 3,400). Fortunately, the classes are not simply jumbled together. The classes of the .NET framework are anized into a hierarchy of namespaces. ASP Classic Note In previous versions of Active Server Pages, you had access to only five standard classes (the Response, Request, Session, Application, and Server objects). , in contrast, provides you with access to over 3,400 classes! A namespace is a logical grouping of classes. For example, all the classes that relate to working with the file system are gathered together into the namespace. The namespaces are anized into a hierarchy (a logical tree). At the root of the tree is the System namespace. This namespace contains all the classes for the base data types, such as strings and arrays. It also contains classes for working with random numbers and dates and times. You can