using System;
using System.Linq.Expressions;
using System.Collections.Generic;
using System.Linq;
using System.Text.RegularExpressions;

public class Test
{
	public static void Main()
	{
		string pattern = @"(?<=\[)[^][]*(?=])|(?<=#)[^#]*(?=#)|[A-Za-z0-9.]+";
		string input = @"add galaxy [Milky way] elliptical 13.2B #test test #";
		
		String[] matches = Regex.Matches(input, pattern)
		           .Cast<Match>()
		           .Select(m => m.Value)
		           .ToArray();
		
		foreach (String m in matches)
		{
		    Console.WriteLine(m);
		}
	}
}