MRE3 Errata Mastering Regular Expressions
Third Edition

Errata
Last updated 14-Jan-2006
Please see my contact information if you'd like to send in an erratum.


p370, last paragraph

Printed:(it renders LF and all the other non-newline...
Fixed: (it renders CR and all the other non-newline...

Reported by Alan Moore, 11-Oct-2006

p447, last paragraph

Printed:..., '+' is treated as '*?' and vice-versa
Fixed: ..., '+' is treated as '+?' and vice-versa

Reported by Jan-Pieter Cornet, 14-Jan-2006

p481, mid-page regex

Printed:  ^((?:<(\w++)[^>]*+(?<!/)>(?1)</\2>|[^<>]++|<\w[^>]*+/>)*+)$</tt>
Fixed:  ^((?:<(\w++)[^>]*+(?<!/)>(?1)</\2>|[^<>]++|<\w[^>]*/>)*+)$</tt>

This is a pretty major error — the use of a possessive greedy quantifier on '[^>]' means that the '/' that follows can never match (since if there were a slash for the '/' to match, the '[^>]' would have consumed it). In an attempt to make the expression a bit more efficient, I made it incorrect, and that's very bad. If PHP had lazy possessive quantifiers, I could use them here, but it doesn't, so the thing to do is to drop the minor efficiency gains from the possessive quantifiers, and use normal greedy quantifiers. That way, it will at least be correct.

Reported by Jan-Pieter Cornet, 14-Jan-2006

p482, middle paragraph

Printed:The third alternative, <\w[^>]*+/>, matches...
Fixed:The third alternative, <\w[^>]*/>, matches...

Reported by Jan-Pieter Cornet, 14-Jan-2006

p482, middle paragraph

Printed:As before, the use of a possessive quantifier here may be overkill but it certainly doesn't hurt.
Fixed:(that sentence removed)

Jan-Pieter pretty much summed this one up when he concluded the errata report with “Ouch.”

Reported by Jan-Pieter Cornet, 14-Jan-2006