XmlWriter.WriteAttributeString Method (String, String, String) (System.Xml)

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Classic
Lightweight
ScriptFree
.NET Framework Class Library
XmlWriter.WriteAttributeString Method (String, String, String)

When overridden in a derived class, writes an attribute with the specified local name, namespace URI, and value.

Namespace:  System.Xml
Assembly:  System.Xml (in System.Xml.dll)
Syntax
Visual Basic
Public Sub WriteAttributeString ( _
	localName As String, _
	ns As String, _
	value As String _
)
C#
public void WriteAttributeString(
	string localName,
	string ns,
	string value
)
Visual C++
public:
void WriteAttributeString(
	String^ localName, 
	String^ ns, 
	String^ value
)
F#
member WriteAttributeString : 
        localName:string * 
        ns:string * 
        value:string -> unit

Parameters

localName
Type: System.String
The local name of the attribute.
ns
Type: System.String
The namespace URI to associate with the attribute.
value
Type: System.String
The value of the attribute.
Exceptions
Exception Condition
InvalidOperationException

The state of writer is not WriteState.Element or writer is closed.

ArgumentException

The xml:space or xml:lang attribute value is invalid.

Remarks

This method writes out the attribute with a user defined namespace prefix and associates it with the given namespace. If localName is "xmlns" then this method also treats this as a namespace declaration. In this case, the ns argument can be null.

WriteAttributeString does the following:

  • If the attribute value includes double or single quotes, they are replaced with " and ' respectively.

  • If writing an xml:space attribute, the writer verifies the attribute value is valid. (Valid values are preserve or default.)

  • If writing an xml:lang attribute, the writer does not verify that the attribute value is valid according to the W3C XML 1.0 recommendation.

Examples

The following example uses the WriteAttributeString method to write a namespace declaration.

Visual Basic

Imports System
Imports System.IO
Imports System.Xml

Public Class Sample 

  Public Shared Sub Main() 

     Dim writer As XmlWriter = Nothing

     writer = XmlWriter.Create("sampledata.xml")

     ' Write the root element.
     writer.WriteStartElement("book")

     ' Write the xmlns:bk="urn:book" namespace declaration.
     writer.WriteAttributeString("xmlns","bk", Nothing,"urn:book")

     ' Write the bk:ISBN="1-800-925" attribute.
     writer.WriteAttributeString("ISBN", "urn:book", "1-800-925")

     writer.WriteElementString("price", "19.95")

     ' Write the close tag for the root element.
     writer.WriteEndElement()

     ' Write the XML to file and close the writer.
     writer.Flush()
     writer.Close()  

  End Sub
End Class
C#

using System;
using System.IO;
using System.Xml;

public class Sample {

  public static void Main() {

     XmlWriter writer = null;

     writer = XmlWriter.Create("sampledata.xml");

     // Write the root element.
     writer.WriteStartElement("book");

     // Write the xmlns:bk="urn:book" namespace declaration.
     writer.WriteAttributeString("xmlns","bk", null,"urn:book");

     // Write the bk:ISBN="1-800-925" attribute.
     writer.WriteAttributeString("ISBN", "urn:book", "1-800-925");

     writer.WriteElementString("price", "19.95");

     // Write the close tag for the root element.
     writer.WriteEndElement();

     // Write the XML to file and close the writer.
     writer.Flush();
     writer.Close();  

  }
}
Visual C++

#using <System.Xml.dll>

using namespace System;
using namespace System::IO;
using namespace System::Xml;
void main()
{
   XmlWriter^ writer = nullptr;
   writer = XmlWriter::Create( L"sampledata.xml" );

   // Write the root element.
   writer->WriteStartElement( L"book" );

   // Write the xmlns:bk="urn:book" namespace declaration.
   writer->WriteAttributeString( L"xmlns", L"bk", nullptr, L"urn:book" );

   // Write the bk:ISBN="1-800-925" attribute.
   writer->WriteAttributeString( L"ISBN", L"urn:book", L"1-800-925" );
   writer->WriteElementString( L"price", L"19.95" );

   // Write the close tag for the root element.
   writer->WriteEndElement();

   // Write the XML to file and close the writer.
   writer->Flush();
   writer->Close();
}
Version Information

.NET Framework

Supported in: 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
Platforms

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.
See Also

Reference

XmlWriter Class
WriteAttributeString Overload
System.Xml Namespace

Other Resources

Writing XML with the XmlWriter