String escape into XML

Question

Is there any C# function which could be used to escape and un-escape a string, which could be used to fill in the content of an XML element?

I am using VSTS 2008 + C# + .Net 3.0.

EDIT 1: I am concatenating simple and short XML file and I do not use serialization, so I need to explicitly escape XML character by hand, for example, I need to put a<b into <foo></foo>, so I need escape string a<b and put it into element foo.

Answer 1

SecurityElement.Escape(string s)

Answer 2

public static string XmlEscape(string unescaped) {     XmlDocument doc = new XmlDocument();     XmlNode node = doc.CreateElement("root");     node.InnerText = unescaped;     return node.InnerXml; }  public static string XmlUnescape(string escaped) {     XmlDocument doc = new XmlDocument();     XmlNode node = doc.CreateElement("root");     node.InnerXml = escaped;     return node.InnerText; }