> This has probably been asked here before (apologies :-)
> What would be a good (excellent) book on regular expressions be?
> Your opinions please.
> Kind regards.
Depends what you call a good book; also, there are regexes and regexes:
Vim regexps are not identical to Perl regexps, and (IIUC) grep regexps
are something else again.
For Vim regexps, whatever book you use or don't use, don't forget ":help
pattern.txt", including the two sections of the user manual to which
there are links in the very first paragraph of pattern.txt. The "formal
definition" of a pattern in section 2 of that helpfile is somewhat
arduous; IMHO the most important part for daily use is the index in
section 4 "pattern-overview", which (in both version 7 and version 6.4
help) comes before section 3 "magic".
The Friedl book is _the_ book to get for a thorough understanding
of regular expressions that will allow you to get the best out of
them and avoid all the common pitfalls. If I recall correctly it
concentrates on Perl5 more than other styles of regex, but the
principles are the same for all flavours of regular expressions.
I'd been using regexes for around fifteen years when I bought the
book and I learned a thing or two from it. It should be required
reading for anyone who uses a product that has regular expressions.
You, too, can do a week's work in a couple of minutes by typing
something that looks like someone dropped a box of punctuation on
to the screen.