When overridden in a derived class, writes out the namespace-qualified name. This method looks up the prefix that is in scope for the given namespace.
Assemblies: System.Xml (in System.Xml.dll)
System.Xml.ReaderWriter (in System.Xml.ReaderWriter.dll)
localName is either nullptr or String.Empty.
localName is not a valid name.
An XmlWriter 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.”
If ns maps to the current default namespace, no prefix is generated.
When writing attribute values, this method generates a prefix if ns is not found. When writing element content, it throws an exception if ns is not found.
If a class derived from the XmlWriter does not override this method localName is not checked to be a valid W3C XML name. In such case, before calling this method, the validity of the string can be checked by IsName method.
For the asynchronous version of this method, see WriteQualifiedNameAsync.
.NET FrameworkSupported in: 4.6, 4.5, 4, 3.5, 3.0, 2.0, 1.1
.NET Framework Client ProfileSupported in: 4, 3.5 SP1
XNA FrameworkSupported in: 3.0, 2.0, 1.0
Portable Class LibrarySupported in: Portable Class Library
Supported in: Windows Phone 8.1
Supported in: Windows Phone Silverlight 8.1
Supported in: Windows Phone Silverlight 8