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XElement.SetAttributeValue Method

Sets the value of an attribute, adds an attribute, or removes an attribute.

Namespace:  System.Xml.Linq
Assemblies:   System.Xml.Linq (in System.Xml.Linq.dll)
  System.Xml.XDocument (in System.Xml.XDocument.dll)

public void SetAttributeValue(
	XName name,
	Object value


Type: System.Xml.Linq.XName

An XName that contains the name of the attribute to change.

Type: System.Object

The value to assign to the attribute. The attribute is removed if the value is null. Otherwise, the value is converted to its string representation and assigned to the Value property of the attribute.


The value is an instance of XObject.

This method is designed to make it easy to maintain a list of name/value pairs as a set of attributes. When maintaining the list, you need to add pairs, modify pairs, or delete pairs. If you call this method passing a name that does not exist as an attribute, this method creates an attribute for you. If you call this method passing the name of an existing attribute, this method modifies the value of the attribute to the value that you specify. If you pass null for value, this method removes the attribute.

This method will raise the Changed and the Changing events.

The value is assigned to the attribute with the specified name. If no attribute with the specified name exists, a new attribute is added. If the value is null, the attribute with the specified name, if any, is deleted.

For more information, see Maintaining Name/Value Pairs.

The following example creates an element with an attribute. It then uses this method to replace the content of the attribute.

// Create an element with no content.
XElement root = new XElement("Root");

// Add some name/value pairs.
root.SetAttributeValue("Att1", 1);
root.SetAttributeValue("Att2", 2);
root.SetAttributeValue("Att3", 3);

// Modify one of the name/value pairs.
root.SetAttributeValue("Att2", 22);

// Remove one of the name/value pairs.
root.SetAttributeValue("Att3", null);

This example produces the following output:

<Root Att1="1" Att2="2" Att3="3" />
<Root Att1="1" Att2="22" Att3="3" />
<Root Att1="1" Att2="22" />

.NET Framework

Supported in: 4.6, 4.5, 4, 3.5

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

XNA Framework

Supported in: 3.0

Portable Class Library

Supported in: Portable Class Library

Supported in: Windows Phone 8.1

Supported in: Windows Phone Silverlight 8.1

Supported in: Windows Phone Silverlight 8
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