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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)

public void WriteAttributeString(
	string localName,
	string ns,
	string value


Type: System.String

The local name of the attribute.

Type: System.String

The namespace URI to associate with the attribute.

Type: System.String

The value of the attribute.


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


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

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.

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

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.

     // 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.

     // Write the XML to file and close the writer.

#using <mscorlib.dll>
#using <System.Xml.dll>
using namespace System;
using namespace System::IO;
using namespace System::Xml;

void main(){
     XmlWriter* writer = 0;

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

     // Write the root element.

     // Write the xmlns:bk="urn:book" namespace declaration.
     writer->WriteAttributeString(S"xmlns",S"bk", 0,S"urn:book");

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

     writer->WriteElementString(S"price", S"19.95");

     // Write the close tag for the root element.

     // Write the XML to file and close the writer.

Windows 7, Windows Vista, Windows XP SP2, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP Starter Edition, Windows Server 2008 R2, Windows Server 2008, Windows Server 2003, Windows Server 2000 SP4, Windows Millennium Edition, Windows 98, 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, 3.0, 2.0, 1.1, 1.0

.NET Compact Framework

Supported in: 3.5, 2.0, 1.0

XNA Framework

Supported in: 3.0, 2.0, 1.0