That is, a class can include a nested class if it needs to. Only certain types support nesting see Chapter 8 for details. I also talk about access levels in that chapter. Each member has an access level that says what code can use that member.
There are five access levels, ranging from Public anybody and their brother can use the member to Private you have to be inside the type to even know it's there. Chapter 6, "Data and Data Types," discusses the. NET type system in greater detail, including the information you crave on classes, structures, and other bananas. Computers are actually quite stupid. While I can count all the way to 17, a computer tops out at 1; it only knows the digits 0 and 1.
The CPU includes a set of simple operators used to manipulate the digits 0 and 1, and a few more operators that compare 1s and 0s in complex ways. The computer's last great trick is its ability to move 0s and 1s into and out of memory, but whoop-dee-doo.
Sure it does these things at nearly the speed of light, but can it calculate p to three million decimal places? Well, actually it can. Computers don't know anything about the letters of the alphabet, and they really only can handle the digits 0 and 1, yet here I am using a computer to write an award-winning book.
It is the ability to combine the simple one-bit data values and operators into increasingly complex libraries of functionality that make useful computers possible. NET Framework is built upon decades of increasingly complex functionality. When you install the. By itself, the framework includes all of the basic functionality needed to let you add 2 and 2 together and correctly get 4. And as a business application developer, you spend a lot of time doing just that. But what if you want to do something more complex, something that you know some other programmer has already done, like sorting a list of names or drawing a colored circle on a form?
To get that answer, go to the class libraries , the. NET Class Libraries. These libraries, installed with the Framework, include a lot of pre-written increasingly complex functionality that you don't have to write from scratch. There are two class libraries in. The BCL is smaller, and contains the most essential features that a program just couldn't do without.
It includes only those classes that are an absolute must for supporting applications on the framework if Microsoft were, say, to port the framework to Linux. The FCL is larger, and includes everything else Microsoft thought you would want to have in your programs, but was not absolutely essential to have in the BCL.
Don't even ask how many classes there are in the FCL; you don't want to know. I bet that Microsoft doesn't even really know the full number. I am convinced that those wacky pranksters at Microsoft have included "gag" classes in the FCL, but they are so deeply buried that few programmers ever encounter them. With thousands yes, thousands! But it's not that difficult, at least not overwhelmingly difficult. NET Framework includes a feature called namespaces. All types in. NET appear in a hierarchy—a tree-like structure—with just a few minimal entries at the root.
Each node in the hierarchy is a namespace. You uniquely identify any class or other type in the libraries by naming all of the namespaces, from the root down to the local namespace that contains the class, separating each node with a period.
Unlike most hierarchies that have all branches starting from a single root node, the. NET namespace hierarchy has multiple root nodes. The largest root namespace is named System. It includes many classes, but it also includes several next-tier hierarchy nodes namespaces.
Because the framework includes features for both Windows-based and Web-based application development, there are namespaces that contain the Windows-specific and Web-specific development features. These namespaces appear just within the System namespace, and are called Windows and Web.
All code related to on-screen Forms in the Windows namespaces appears in the Forms namespace, and within this namespace is the actual class that implements a form, named Form. Figure presents an image of this namespace subset. Figure A hierarchy of namespaces and classes. In Visual Basic, you identify a class by qualifying it with all of its namespaces, starting from its root namespace.
The Form class has the following fully qualified name:. All classes and types exist somewhere in the hierarchy, although not every class descends from System. Many of the supporting features specific to Visual Basic appear in the Microsoft. VisualBasic namespace, which has "Microsoft" as its root node instead of "System. If you create a new Windows application, the default "Form1" form has the following fully qualified name:.
This new application's namespace is not just a second-class appendage hanging off of the System namespace. It is fully integrated into the full. NET namespace hierarchy; the WindowsApplication1 namespace is a root node, just like the System and Microsoft root nodes.
Visual Basic includes features that let you alter the default namespace for your application, or place one of the application's classes in a specific namespace. You can even place your application's classes in the System namespace branch. Changing WindowsApplication1 to System. MySuperApp moves Form1 to:. If your application is actually a component or library destined for use in programs, your app's classes will appear in the namespace you specify when the other program loads your component into its application area.
Your code will look like it is part of the Microsoft-supplied namespaces. Is that cool or what? Although you can add your classes to the System namespace, you will incur the wrath of other.
NET programmers. The System namespace is supposed to be for "system" read: Microsoft-supplied features, and that's it. Also, there's a chance that two vendors might use the same namespace path.
So, to avoid potential namespace conflicts and dirty looks from other programmers, you should name your application's classes as:. A single class or other type cannot be split across multiple namespaces, even within the same hierarchy branch. However, two classes or types may share a common name in different namespaces, even within the same branch.
Frankly, it doesn't really matter; your code won't care which library a class comes from, as long as it is available for use on the user's workstation. An assembly is a "unit of deployment" for the parts of a. NET application or library. In NET executable file an "exe" file or a.
NET library of classes and other types a "dll" file. It is possible to split an assembly between multiple files, but usually it is one file for one assembly. What makes an ordinary exe or dll file an assembly is the presence of a manifest. For single-file assemblies, the manifest appears right in the file; it can also appear in a file of its own. The manifest is a chunk of data that lists important details about the assembly, including its name, version information, default culture, information on referencing external assemblies and types, and a list of all the files contained in the assembly.
The CLR will not recognize an assembly without its manifest, so don't lose it. Assemblies can include an optional strong name. This helps to ensure the integrity and authenticity of an assembly through a digital signature attached to the manifest. The strong name uses public key cryptography to guarantee that the assembly is unique and has not been tampered with. Visual Studio and the. NET Framework include tools that let you add a strong name to an assembly.
When you deploy your application, you will normally place all assembly files, configuration files, and any related files specific to your application in the application's install directory, just like in the old Jurassic days before. Shared assemblies designed to be used by more than one application on a single machine can be stored in the global assembly cache GAC.
All assemblies placed in the GAC must have strong names. Some systems may only allow the system administrator to add assemblies to the GAC. Assemblies are brought to you by the letter "m. The application code and data elements stored in an assembly parallel the code and data items found in the related Visual Basic source code; for each type and member in your source code, there is associated executable code in the deployed assembly.
This makes sense, and is not much of a change from pre-. NET deployments. What is different is that the Visual Basic compiler now attaches additional information—metadata—to each type and member in the assembly. This metadata documents the name of the associated content, information about required data types, information on class inheritance for the element, and security permissions required before the element can be used by the user or other software.
Your Visual Basic source code can enhance the metadata for any element of your assembly through attributes. The metadata generated by an attribute is more than just some ID number. Attributes implement full. NET classes, with their own data values and associated logic. NET code that knows how to process attributes can examine the attributes for a type or member and take action as needed.
NET Framework is a technology that supports building and running Windows apps and web services. NET Framework is designed to fulfill the following objectives:. Provide a consistent, object-oriented programming environment whether object code is stored and executed locally, executed locally but web-distributed, or executed remotely. Promotes safe execution of code, including code created by an unknown or semi-trusted third party. Make the developer experience consistent across widely varying types of apps, such as Windows-based apps and Web-based apps.
Build all communication on industry standards to ensure that code based on. NET Framework integrates with any other code. NET Framework 4. NET Framework. NET Framework is serviced monthly with security and reliability bug fixes. NET Framework will continue to be included with Windows, with no plans to remove it.
You don't need to migrate your. NET Framework apps, but for new development, use. NET 5 or later. NET Framework class library. The common language runtime is the foundation of. Think of the runtime as an agent that manages code at execution time, providing core services such as memory management, thread management, and remoting, while also enforcing strict type safety and other forms of code accuracy that promote security and robustness. In fact, the concept of code management is a fundamental principle of the runtime.
Code that targets the runtime is known as managed code, while code that doesn't target the runtime is known as unmanaged code. The class library is a comprehensive, object-oriented collection of reusable types that you use to develop apps ranging from traditional command-line or graphical user interface GUI apps to apps based on the latest innovations provided by ASP. NET Framework can be hosted by unmanaged components that load the common language runtime into their processes and initiate the execution of managed code, thereby creating a software environment that exploits both managed and unmanaged features.
NET Framework not only provides several runtime hosts but also supports the development of third-party runtime hosts. For example, ASP. NET hosts the runtime to provide a scalable, server-side environment for managed code. Internet Explorer is an example of an unmanaged app that hosts the runtime in the form of a MIME type extension. Hosting the runtime in this way makes managed mobile code possible, but with significant improvements that only managed code offers, such as semi-trusted execution and isolated file storage.
The following illustration shows the relationship of the common language runtime and the class library to your apps and to the overall system. The illustration also shows how managed code operates within a larger architecture. The common language runtime manages memory, thread execution, code execution, code safety verification, compilation, and other system services. I used for the number of classes see update 3 below. Unfortunately the full text of the paper is not freely available, only the abstract.
Update 3 : I think I have come very close to a solution now: public classes for. Extending on update 1, I have made the function recursive and extended it so the number of types, classes and public classes are reported for any sub-folder and its subfolders. NET gives types, only 0. Full transcript - HTML source is tab separated so it can be imported into a spreadsheet, e. OpenOffice Calc. Here is a break-down for public classes:. This was on a different system than for the programmatic solution see below.
Engine", "Microsoft. Framework", "Microsoft. Tasks", "Microsoft. Utilities", "Microsoft. JScript", "Microsoft. VisualBasic", "Microsoft. Compatibility", "Microsoft. Data", "Microsoft. Vsa", "Microsoft. VisualC", "Microsoft. Install", "System. Data", "System. OracleClient", "System. SqlXml", "System. Deployment", "System. Design", "System. DirectoryServices", "System. Protocols", "System. Drawing", "System. EnterpriseServices", "System.
Management", "System. Messaging", "System. Remoting", "System. Soap", "System. Security", "System. ServiceProcess", "System. Transactions", "System. Web", "System. Mobile", "System. RegularExpressions", "System.
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