"Let's say that we want to create a regex pattern to search for hexadecimal literals. As
a first step, let's solve the problem for one-digit hexadecimal numbers:
This is from Kathy Sierra and Bates SCJP book page 492 regarding regex. I don't quite understand why the index goes from 0 to 9, then from 0 to 7 rather than from 0 to 18. And the explanation says that the regex returns position 6 and 11, but I don't see any 11. What am I missing?