[.net] (solved) C# -- NullReference Exception when returning array...

using System;
using System.IO; // console.writeline, file system enumeration, etc.
using System.Text; // encoding.utf8
using System.Xml; // xmltextwriter

namespace fs2xml
{
	class entry_point
	{
		// XML document object for writing out enumerated file system info
		static protected XmlTextWriter xml_writer;

		[STAThread]
		static int Main(string[] args)
		{
			// check to see we have a directory name, and an output XML file name
			if(2 != args.Length)
			{
				Console.WriteLine("Usage:"); 
				Console.WriteLine("  fs2xml directory_name output_xml_file_name"); 
				return -1;
			}

			// scratch variables
			String dir_name = args[0];
			String xml_file = args[1];
	
			// test that initial directory even exists
			if(false == Directory.Exists(dir_name))
			{
				Console.WriteLine("Error: " + dir_name + " does not exist.");
				return -2;
			}

			// create the XML document, start with a root element of "listing"
			xml_writer = new XmlTextWriter(xml_file, Encoding.UTF8);
			xml_writer.WriteStartDocument();
			xml_writer.WriteStartElement("listing");

			// recursively dump file and subdir listing to xml file
			dir_list_to_xml(dir_name);

			// cleanup
			xml_writer.WriteEndElement();
			xml_writer.WriteEndDocument();
			xml_writer.Close();

			return 0;
		}

		// list files in current directory, as well as subdirectories and their contents
		static void dir_list_to_xml(String dir_name)
		{
			// sanity check / ease of use later down the road in concatenation ops
			if('\\' != dir_name[dir_name.Length - 1])
				dir_name += '\\';

			// list the files
			fs_item_info[] file_list = get_file_list(dir_name);

			for(int i = 0; i < file_list.Length; i++)
			{
				xml_writer.WriteStartElement("file");
				xml_writer.WriteElementString("name", file_list.name);
				xml_writer.WriteElementString("last_mod", file_list.last_modified.ToString());
				xml_writer.WriteEndElement();
			}

			// list the subdirs
			fs_item_info[] dir_list = get_sub_dir_list(dir_name);

			// recursively call this same function for each subdir found
			for(int i = 0; i < dir_list.Length; i++)
			{
				xml_writer.WriteStartElement("directory");
				xml_writer.WriteElementString("name", dir_list.name);
				xml_writer.WriteElementString("last_mod", dir_list.last_modified.ToString());

				dir_list_to_xml(dir_name + dir_list.name);

				xml_writer.WriteEndElement();
			}
		}

		// get file info array
		static fs_item_info[] get_file_list(string dir_name)
		{
			DirectoryInfo root_dir = new DirectoryInfo(dir_name);
			FileInfo[] files = root_dir.GetFiles("*.*");

			fs_item_info[] fsi = new fs_item_info[files.Length];

			for(int i = 0; i < files.Length; i++)
			{
				fsi.name = files.Name;
				fsi.last_modified = files.LastWriteTime;
			}

			//return (fs_item_info[])fsi.Clone();
			return fsi; // ?????
		}

		// get subdir info array
		static fs_item_info[] get_sub_dir_list(string dir_name)
		{
			DirectoryInfo root_dir = new DirectoryInfo(dir_name);
			DirectoryInfo[] sub_dirs = root_dir.GetDirectories("*.*");

			fs_item_info[] fsi = new fs_item_info[sub_dirs.Length];

			for(int i = 0; i < sub_dirs.Length; i++)
			{
				fsi.name = sub_dirs.Name;
				fsi.last_modified = sub_dirs.LastWriteTime;
			}

			return fsi;
		}
	}

	// all file/dir info one needs should go in here
	class fs_item_info
	{
		public String name = "";
		public DateTime last_modified = DateTime.MinValue;
	}
}