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XName Class

Represents a name of an XML element or attribute.

Namespace:  System.Xml.Linq
Assembly:  System.Xml.Linq (in System.Xml.Linq.dll)

[SerializableAttribute]
public sealed class XName : IEquatable<XName>, 
	ISerializable

XML names include a namespace and a local name. A fully qualified name is the combination of the namespace and local name.

Creating an XName Object

XName does not contain any public constructors. Instead, this class provides an implicit conversion from String that allows you to create an XName. The most common place you use this conversion is when constructing an element or attribute: The first argument to the XElement constructor is an XName. By passing a string, you take advantage of the implicit conversion. The following code creates an element with a name that is in no namespace:

XElement root = new XElement("ElementName", "content");
Console.WriteLine(root);

In Visual Basic, it is more appropriate to use XML literals:

Dim root As XElement = <ElementName>content</ElementName>
Console.WriteLine(root)

This example produces the following output:

<ElementName>content</ElementName>

Assigning a string to an XName uses the implicit conversion from String.

The Visual Basic example creates the XElement using XML literals. Even though XML literals are used, an XName object is created for the XElement.

In addition, you can call the Get method for an XName object. However, the recommended way is to use the implicit conversion from string.

Creating an XName in a Namespace

As with XML, an XName can be in a namespace, or it can be in no namespace.

For C#, the recommended approach for creating an XName in a namespace is to declare the XNamespace object, then use the override of the addition operator.

For Visual Basic, the recommended approach is to use XML literals and global namespace declarations to create XML that is in a namespace.

XNamespace aw = "http://www.adventure-works.com";
XElement root = new XElement(aw + "ElementName", "content");
Console.WriteLine(root);

This example produces the following output:

<ElementName xmlns="http://www.adventure-works.com">content</ElementName>

Creating an XName in no Namespace

The Namespace property of an XName object is guaranteed to not be null. If the XName is in no namespace, then the Namespace property will be set to None. The following code demonstrates this:

XElement root = new XElement("ElementName", "content");
if (root.Name.Namespace == XNamespace.None)
    Console.WriteLine("The element is in no namespace.");
else
    Console.WriteLine("The element is in a namespace.");

This example produces the following output:

The element is in no namespace.

Using Expanded Names

You can also create an XName from a expanded XML name in the form {namespace}localname:

XElement root = new XElement("{http://www.adventure-works.com}ElementName", "content");
Console.WriteLine(root);

This example produces the following output:

<ElementName xmlns="http://www.adventure-works.com">content</ElementName>

Be aware that creating an XName through an expanded name is less efficient than creating an XNamespace object and using the override of the addition operator. It is also less efficient than importing a global namespace and using XML literals in Visual Basic.

If you create an XName using an expanded name, LINQ to XML must find the atomized instance of a namespace. This work must be repeated for every use of an expanded name. This additional time is likely to be negligible when writing LINQ queries; however, it might be significant when creating a large XML tree.

XName Objects are Atomized

XName objects are guaranteed to be atomized; that is, if two XName objects have exactly the same namespace and exactly the same local name, they will share the same instance. The equality and comparison operators are also provided explicitly for this purpose.

Among other benefits, this feature allows for faster execution of queries. When filtering on the name of elements or attributes, the comparisons expressed in predicates use identity comparison, not value comparison. It is much faster to determine that two references actually refer to the same object than to compare two strings.

System.Object
  System.Xml.Linq.XName

Any public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.

Windows 7, Windows Vista, Windows XP SP2, Windows Server 2008 R2, Windows Server 2008, Windows Server 2003, Windows CE, Windows Mobile for Smartphone, Windows Mobile for Pocket PC, Xbox 360, Zune

The .NET Framework and .NET Compact Framework do not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

.NET Framework

Supported in: 3.5

.NET Compact Framework

Supported in: 3.5

XNA Framework

Supported in: 3.0

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