Prepending a child node adds the new node to the beginning of the list of child nodes for the current node. For example, when three child nodes exist for an element, the prepended node becomes the first child node. If no child nodes exist, then a new child node is created.

Namespace prefix and URI values can be obtained by using the XPathNavigator.LookupPrefix(string) or XPathNavigator.LookupNamespace(string) method. For example, the following syntax prepends a child element by using the in-scope namespace xmlns:bk="http://www.contoso.com/books":

navigator.PrependChildElement(navigator.Prefix, "pages", LookupNamespaceURI(navigator.Prefix), String.Empty)

This creates the new child <bk:pages/> element.

The following are important notes to consider when using the XPathNavigator.PrependChildElement(string, string, string, string) method.

• If the namespace prefix specified is null or string.Empty, then the prefix for the namespace URI of the new element is obtained from the current namespaces in-scope. If there is no namespace prefix assigned to the specified namespace URI at the current scope, then a namespace prefix is automatically generated.

• The XPathNavigator.PrependChildElement(string, string, string, string) method is valid only when the System.Xml.XPath.XPathNavigator is positioned on an element node.

• The XPathNavigator.PrependChildElement(string, string, string, string) method does not affect the position of the System.Xml.XPath.XPathNavigator.