public class Folders
{


public static IEnumerable<string> FolderNames(string xml, char startingLetter)
{
    string[] MyString;
    List<string> MyList = new List<string>();
    string item = "";

   StringSplitOptions.None)).ToList();

    MyString = xml.Split('>') ;

    var matchingvalues = MyString
.Where(stringToCheck => stringToCheck.Contains("<folder name=\""));

     return matchingvalues;
}

public static void Main(string[] args)
{
    string xml =
        "<?xml version="1.0" encoding="UTF-8"?>" +
        "<folder name="c">" +
            "<folder name="program files">" +
                "<folder name="uninstall information" />" +
            "</folder>" +
            "<folder name="users" />" +
        "</folder>";


      foreach (string name in Folders.FolderNames(xml, 'u'))
    Console.WriteLine(name);
    Console.ReadLine();
}