Use wildcard characters * and ? to compare strings

Using the Substring operation repeatedly as you do is apt to be very slow. Better would be to pass the starting indices and lengths of the two strings as parameters. That would require a manual loop to replace the String.Trim function, but it would avoid the need to create lots of new string objects on the heap. For short strings it wouldn't matter too much, but I would expect your routine would get really slow if the strings are a few thousand characters long.