You need to do something like this:
// instantiate XmlDocument and load XML from file
XmlDocument doc = new XmlDocument();
doc.Load(@"D:\test.xml");
// get a list of nodes - in this case, I'm selecting all <AID> nodes under
// the <GroupAIDs> node - change to suit your needs
XmlNodeList aNodes = doc.SelectNodes("/Equipment/DataCollections/GroupAIDs/AID");
// loop through all AID nodes
foreach (XmlNode aNode in aNodes)
{
// grab the "id" attribute
XmlAttribute idAttribute = aNode.Attributes["id"];
// check if that attribute even exists...
if (idAttribute != null)
{
// if yes - read its current value
string currentValue = idAttribute.Value;
// here, you can now decide what to do - for demo purposes,
// I just set the ID value to a fixed value if it was empty before
if (string.IsNullOrEmpty(currentValue))
{
idAttribute.Value = "515";
}
}
}
// save the XmlDocument back to disk
doc.Save(@"D:\test2.xml");