【導(dǎo)讀】C#程序語言是建立在C和C++程序語言的精神上的。這個(gè)賬目有著很有力的特征和。不能說C#與C和C++相同，但是因?yàn)镃#是建立在這兩者之上，微軟移除了。一些成為更多負(fù)擔(dān)的特征，比如說指針。這部分觀看C和C++，在C#中追蹤它們的發(fā)展。C程序語言原本是被定義在UNIX操作系統(tǒng)中的。括一個(gè)C編譯器，最后被用于寫UNIX自己。它普遍認(rèn)可在這個(gè)學(xué)術(shù)上的競(jìng)爭(zhēng)擴(kuò)展到包含。并且直到今天至少設(shè)置核心的Windows操作系統(tǒng)APIS保持C編譯器。不能被強(qiáng)制出現(xiàn)在這個(gè)語言中。C++被開發(fā)出，包含了。譯器編譯）C++語言主要的增加是提供這種新的概念。C++又額外提供了的類（對(duì)象的。C++可以處理在一些非常給力的應(yīng)用程序中，碼工作的很流暢。C的兼容，C++不能夠打破C的底層特性。對(duì)于C#來說一個(gè)很大的優(yōu)勢(shì)是它的設(shè)計(jì)師并沒有讓它去兼容C和C++。是個(gè)錯(cuò)誤的處理時(shí)，事實(shí)上是一個(gè)好消息。因此它能夠保持前輩的強(qiáng)項(xiàng)并且丟棄使得C和C++程序生存困難的弱點(diǎn)。C#這門在.NET體系中被引進(jìn)的全新語言，是從C++衍生出來的。

　　

【正文】 ndheld. You now have a single MSIL code base that can run on any device that has a .NET JIT piler. The JIT piler on that device takes care of making your code run on the device. Another reason for the piler39。s use of MSIL is that the instruction set can be easily read by a verification process. Part of the job of the JIT piler is to verify your code to ensure that it is as clean as possible. The verification process ensures that your code is accessing memory properly and that it is using the correct variable types when calling methods that expect a specific type. These checks ensure that your code doesn39。t execute any instructions that could make the code crash. The MSIL instruction set was designed to make this verification process relatively straightforward. CPUspecific instruction sets are optimized for quick execution of the code, but they produce code that can be hard to read and, therefore, hard to verify. Having a C piler that directly outputs CPUspecific code can make code verification difficult or even impossible. Allowing the .NET Framework JIT piler to verify your code ensures that your code accesses memory in a bugfree way and that variable types are properly used. Metadata The pilation process also outputs metadata, which is an important piece of the .NET code sharing story. Whether you use C to build an enduser application or you use C to build a class library to be used by someone else39。s application, you39。re going to want to make use of some alreadypiled .NET code. That code may be supplied by Microsoft as a part of Framework, or it may be supplied by a user over the Inter. The key to using this external code is letting the C piler know what classes and variables are in the other code base so that it can match up the source code you write with the code found in the prepiled code base that you39。reworking with. Think of metadata as a table of contents for your piled code. The C piler places metadata in the piled code along with the generated MSIL. This metadata accurately describes all the classes you wrote and how they are structured. All of the classes39。 methods and variable information is fully described in the metadata, ready to be read by other applications. Visual Bas ic .NET, for example, may read the metadata for a .NET library to provide the IntelliSense capability of listing all of the methods available for a particular class. If you39。ve ever worked with COM (Component Object Model), you may be familiar with type libraries. Type libraries aimed to provide similar table of contents functionality for COM objects. However, type libraries suffered from some limitations, not the least of which was the fact that not all of the data relevant to the object was put into the type library. Metadata does not have this shorting. All of the information needed to describe a class in code is placed into the metadata. You can think of metadata as having all of the benefits of COM type libraries without the limitations . Assemblies Sometimes, you will use C to build an enduser application. These applications are packaged as executable files with an extension of .EXE. Windows has always worked with .EXE files as application programs, and C fully supports building .EXE files. However, there may be times when you don39。t want to build an entire application. Instead, you may want to build a code library that can be used by others. You may also want to build some utility classes in C, for example, and then hand the code off to a Visual Bas ic .NET developer, who will use your classes in a Visual Basic .NET application. In cases like this, you won39。t be building an application. Instead, you39。ll be building an assembly. An assembly is a package of code and metadata. When you deploy a set of classes in an assembly, you are deploying the classes as a unit。 and those classes share the same level of version control, security information, and activation requirements. Think of an assembly as a logical DLL. If you39。re familiar with Microsoft Transaction Server or COM+, you can think of an assembly as the .NET equivalent of a package. There are two types of assemblies: private assemblies and global assemblies. When you build your assembly, you don39。t need to specify whether you want to build a private or a global assembly. The difference is apparent when you deploy your assembly. With a private assembly, you make your code available to a single application. Your assembly is packaged as a DLL, and is installed into the same directory as the application using it. With a deployment of a private assembly, the only application that can use your code is the executable that lives in the same directory as your assembly. If you want to share your code among many applications, you might want to consider deploying your code as a global assembly. Global assemblies can be used by any .NET application on the system, regardless of the directory in which it is installed. Microsoft ships assemblies as a part of the .NET Framework, and each of the Microsoft assemblies is installed as a global assembly. The .NET Framework contains a list of global assemblies in a facility called the global assembly cache, and the .NET Microsoft Framework SDK includes utilities to both install and remove assemblies from the global assembly cache. In one sense, C can be seen as being the same thing to programming languages as .NET is to the Windows environment. Just as Microsoft has been adding more and more features to Windows and the Windows API over the past decade, Visual Bas ic and C++ have undergone expansion. Although Visual Basic and C++ have ended up as hugely powerful languages as a result of this, both languages also suffer from problems due to the legacies of how they have evolved. In the case of Visual Basic 6 and earlier, the main strength