On Fri, 10 Jul 2009, Matthias B. wrote:

> I've read about the recursion feature in pcre.txt. I also tried it with
> simple expressions like "\w(?R)" - shouldn't that match the same like
> "\w\w"? 

No.

>It doesn't and I don't understand why. Can you mention that to me?

A usable recursive regex, like a recursive function in a programming
language, must have some way of stopping the recursion. Your pattern 
goes on for ever. It matches an infinite number of \w (which is of 
course impossible). A slightly different pattern:

\w($|(?R))

is the same as 

\w+

Notice the option for stopping when the end of the text is reached.

Philip

-- 
Philip Hazel

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