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XPathNavigator.LookupPrefix Method

Gets the prefix declared for the specified namespace URI.

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

public virtual string LookupPrefix(
	string namespaceURI


Type: System.String
The namespace URI to resolve for the prefix.

Return Value

Type: System.String
A String that contains the namespace prefix assigned to the namespace URI specified; otherwise, String.Empty if no prefix is assigned to the namespace URI specified. The String returned is atomized.



The LookupPrefix method returns the first prefix that matches the namespace URI specified. Multiple prefixes referring to the same namespace URI are not ordered in any particular way, so a particular prefix may not be returned each time when more than one is assigned.


Namespace URI to prefix mappings can change from node to node in an XML document. As a result, the value of the LookupPrefix method may not be consistent from one node to the next.

.NET Framework

Supported in: 4, 3.5, 3.0, 2.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows XP SP2 x64 Edition, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2

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