New page in Visual C#

Encode Data Matrix ECC200 in Visual C# New page

The previous example used a separate method and a delegate to attach the code to the operator. This required declaring the method, declaring the delegate object, and then passing the delegate object to the operator. This works fine, and is exactly the right approach to take if either of the following conditions is true: If the method must be called from somewhere else in the program than just in the place it is used to initialize the delegate object If the code in the method body is more than just a statement or two long If neither of these conditions is true, however, you probably want to use a more compact and localized method of supplying the code to the operator, using a lambda expression as described in 15. We can modify the previous example to use a lambda expression by first deleting the IsOdd method entirely, and placing the equivalent lambda expression directly at the declaration of the delegate object. The new code is shorter and cleaner, and looks like this: class Program { static void Main() { int[] intArray = new int[] { 3, 4, 5, 6, 7, 9 }; Lambda expression var countOdd = intArray.Count( x => x % 2 == 1 ); Console.WriteLine("Count of odd numbers: {0}", countOdd); } } Like the previous example, this code produces the following output:

Count of odd numbers: 4

We could also have used an anonymous method in place of the lambda expression, as shown following. This is more verbose, though, and since lambda expressions are equivalent semantically and are less verbose, there s little reason to use anonymous methods anymore. class Program { static void Main( ) { int[] intArray = new int[] { 3, 4, 5, 6, 7, 9 }; Anonymous method Func<int, bool> myDel = delegate(int x) { return x % 2 == 1; }; var countOdd = intArray.Count(myDel); Console.WriteLine("Count of odd numbers: {0}", countOdd); } }

Over the last several years, XML (Extensible Markup Language) has become an important method of storing and exchanging data. C# 3.0 adds features to the language that make working with XML much easier than previous methods such as XPath and XSLT. If you re familiar with these methods, you might be pleased to hear that LINQ to XML simplifies the creation, traversal, and manipulation of XML in a number of ways, including the following: You can create an XML tree in a top-down fashion, with a single statement. You can create and manipulate XML in-memory without having an XML document to contain the tree. You can create and manipulate string nodes without having a Text sub-node. Although I won t give a complete treatment of XML, I will start by giving a very brief introduction to it before describing some of the XML-manipulation features introduced with C# 3.0.

A markup language is a set of tags placed in a document to give information about the information in the document. That is, the markup tags are not the data of the document they contain data about the data. Data about data is called metadata. A markup language is a defined set of tags designed to convey particular types of metadata about the contents of a document. HTML, for example, is the most widely known markup language. The metadata in its tags contains information about how a web page should be rendered in a browser, and how to navigate among the pages using the hypertext links. While most markup languages contain a predefined set of tags XML contains only a few defined tags, and the rest are defined by the programmer to represent whatever kinds of metadata are required by a particular document type. As long as the writer and reader of the data agree on what the tags mean, the tags can contain whatever useful information the designers want.