【導(dǎo)讀】C#,讀作“seesharp”——是專門為.NET平臺設(shè)計(jì)的編程語言。以來，C#創(chuàng)建了許多角色。它廣泛的應(yīng)用于網(wǎng)站服務(wù)器端以及windows桌面應(yīng)用程序的客。戶端和服務(wù)器上。為了很好的了解一種語言并且有效的應(yīng)用，僅僅專注于細(xì)節(jié)。并且我們將在了解C#的最新演變——第四個版本，中結(jié)束此章節(jié)。以比以前更加有效或者在更大的規(guī)模上得到解決。程人員的編程傳統(tǒng)相似，如JavaScript和Java繪制。數(shù)聲明和流量控制，盡量與C家族語言接近。問題的暴政中解救出來，如內(nèi)存泄漏和循環(huán)引用。但是C或C++的windows開發(fā)人員可能不習(xí)慣這些功能，他。環(huán)境、C#庫以及所有其他.NET語言，就像。C#是為.NET設(shè)計(jì)的，他們之間關(guān)系如。C#并不是唯一一個在.NETFramwork上運(yùn)行的語言。C++相比，它支持原始語言的.NET的擴(kuò)展。但C＃在這方面并不是獨(dú)樹一幟的。這是一個功能性編程語言，嚴(yán)重影響由毫升語言。算法，有一些特點(diǎn)，可以幫助并行執(zhí)行。然而，與許多語言功能，使一些困難的問題更容

　　

【正文】 ng. Windows is perhaps the most striking example of this phenomenon. Any new programming system attempting to gain acceptance has a considerable advantage if it can plug into some existing ecosystem, and one of the biggest differences between C and Java is that C and the .NET Framework positively embrace the Windows platform, while Java goes out of its way to insulate developers from the underlying OS. If you’re writing code to run on a specific operating system, it’s not especially helpful for a language to cut you off from the tools and ponents unique to your chosen platform. Rather than requiring developers to break with the past, .NET offers continuity by making it possible to work directly with ponents and services either built into or built for Windows. Most of the time, you won’t need to use thisthe class library provides wrappers for a lot of the underlying platform’s functionality. However, if you need to use a thirdparty ponent or a feature of the operating system that doesn’t yet have a .NET wrapper, the ability to work with such unmanaged features directly from managed code is invaluable. While .NET offers features to ease integration with the underlying platform, there is still support for nonWindows systems. Microsoft’s Silverlight can run C and code on Mac OS X as well as Windows. There’s an open source project called Mono which enables .NET code to run on Linux, and the related Moonlight project is an open source version of Silverlight. So the presence of local platform integration features doesn’t stop C from being useful on multiple platformsif you want to target multiple operating systems, you would just choose not to use any platformspecific features. So the biggest philosophical difference between C and Java is that C provides equal support for direct use of operatingsystemspecific features and for platform independence. Java makes the former disproportionately harder than the latter. The latest version of C contains features that enhance this capability further. Several of the new C features make it easier to interact with Office and other Windows applications that use COM automationthis was a weak spot in C . The relative ease with which developers can reach outside the boundaries of managed code makes C an attractive choiceit offers all the benefits of managed execution, but retains the ability to work with any code in the Windows environment, managed or not. C , .NET 4, and Visual Studio 2020 Since C favors generalpurpose language features designed to be posed with one another, it often doesn’t make sense to describe individual new features on their own. So rather than devoting sections or whole chapters to new features, we cover them in context, integrated appropriately with other, older language features. The section you’re reading right now is an exception, of course, and the main reason is that we expect people already familiar with C to browse through this book in bookstores looking for our coverage of the new features. If that’s you, wele to the book! If you look in the Preface you’ll find a guide to what’s where in the book, including a section just for you, describing where to find material about C features. That being said, a theme unites the new language features in version 4: they support dynamic programming, with a particular focus on making certain interoperability scenarios simpler. For example, consider the C code in Example 13 that uses part of the Office object model to read the Author property from a Word document. Example 13. The horrors of Office interop before C static void Main(string[] args) { var wordApp = new ()。 object fileName = @。 object missing = 。 C , .NET 4, and Visual Studio 2020 | 7 Download from Library of Wow! eBook object readOnly = true。 doc = (ref fileName, ref missing, ref readOnly, ref missing, ref missing, ref missing, ref missing, ref missing, ref missing, ref missing, ref missing, ref missing, ref missing, ref missing, ref missing, ref missing)。 object docProperties = 。 Type docPropType = ()。 object authorProp = (Item, | ,null, docProperties,new object[] { Author })。 Type propType = ()。 string authorName = (Value, |,null, authorProp,new object[] { }).ToString()。 object saveChanges = false。 (ref saveChanges, ref missing, ref missing)。 (authorName)。 } That’s some pretty horrible codeit’s hard to see what the example does because the goal is lost in the details. The reason it is so unpleasant is that Office’s programming model is designed for dynamic languages that can fill in a lot of the details at runtime. C wasn’t able to do this, so developers were forced to do all the work by hand. Example 14 shows how to do exactly the same job in C . This is a lot easier to follow, because the code contains only the relevant details. It’s easy to see the sequence of operationsopen the document, get its properties, retrieve the Author property’s value, and close the document. C is now able to fill in all the details for us, thanks to its new dynamic language features. Example 14. Office interop with C static void Main(string[] args) { var wordApp = new ()。 doc = (, ReadOnly: true)。 dynamic docProperties = 。 string authorName = docProperties[Author].Value。 (SaveChanges: false)。 (authorName)。 } 指導(dǎo)教師評語： 簽名： 年 月 日