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XmlReader.LookupNamespace Method

When overridden in a derived class, resolves a namespace prefix in the current element's scope.

Namespace:  System.Xml
Assemblies:   System.Xml (in System.Xml.dll)
  System.Xml.ReaderWriter (in System.Xml.ReaderWriter.dll)

public abstract string LookupNamespace(
	string prefix
)

Parameters

prefix
Type: System.String

The prefix whose namespace URI you want to resolve. To match the default namespace, pass an empty string.

Return Value

Type: System.String
The namespace URI to which the prefix maps or null if no matching prefix is found.

ExceptionCondition
InvalidOperationException

An XmlReader method was called before a previous asynchronous operation finished. In this case, InvalidOperationException is thrown with the message “An asynchronous operation is already in progress.”

In the following XML string, if the reader is positioned on the href attribute, the prefix a is resolved by calling reader.LookupNamespace("a"). The returned string is urn:456.

<root xmlns:a="urn:456">
  <item>
  <ref href="a:b"/>
  </item>
 </root>

.NET Framework

Supported in: 4.6, 4.5, 4, 3.5, 3.0, 2.0, 1.1, 1.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Portable Class Library

Supported in: Portable Class Library

.NET for Windows Store apps

Supported in: Windows 8

Supported in: Windows Phone 8.1

Supported in: Windows Phone Silverlight 8.1

Supported in: Windows Phone Silverlight 8

Windows Phone 8.1, Windows Phone 8, Windows 8.1, Windows Server 2012 R2, Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)

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

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