Great, another example of regex engines not doing anything you tell them. I'll look at changing it but () isn't going to work there it has to be taught later.
the solution seems pretty easy. simply leave out the beginning/end-of-line assertions. [0-9]+|[A-Z]+ would suffice for that example. i agree that introducing capture groups IS too early, but you can add the parentheses without mentioning capture groups, even if they do capture. grouping still has great value as a precedence indicator which is taught in gradeschool arithmetic.
it's rather unfortunate that the syntax to capture is "(" while the less complex no-capture is "(?:", i'm not sure who thought that through, but here we are.
Yes, I hate that (?:) syntax. Who the hell thought that crap up.
But, I will point out that you attributed the error to NL/EOL assertion, when actually it was order of precedence of | being greater than $ and ^. It's a simple nearly 1-2 character mistake, not a "novice" mistake that discredits the entire book.
yeah i apologize, perhaps i was a bit harsh. i did understand what the issue was and never claimed that it was the newline/EOL assertion itself. i said that your newline/EOL assertion is being treated as PART of the alteration, which is exactly what happens - yes because of pipe's higher operator precedence when no explicit grouping is defined.
novice or not though, 2 misplaced chars in a regex can make the diff between a security feature and a security hole, in this case matching a plethora of inject-able, potentially malicious characters which appear nowhere in the regex, not even as a wildcard ".", i would never make the claim that a 2-char mistake which matches this far beyond its intent is a minor oversight in a real-world, public facing application - and isn't that the ultimate goal?
the only issue in the context of a book for a regex beginner is that the regex gives the appearance of newline/EOL assertion hugging an alteration, but does something quite different. removing those assertions would clear things up for the better.
