Yes. I'd kinda worked that out, and the lookahead assertion works ok, but I was really asking why don't they work in character classes? I mean there ae plenty of other ways of denoting a character, even the non-printable ones: 

chr(0) => \cA, \01 \x01

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It seems a shame to have to use a lookahead assertion and (.) to ([^\1])... and I was wondering if there was any reason other than "that's the way it is"?

Examine what is said, not who speaks.
"Efficiency is intelligent laziness." -David Dunham
"Think for yourself!" - Abigail

In reply to Re: Re: Regex backreference problem. by BrowserUk
in thread Regex backreference problem. by BrowserUk

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