Re: /(foo|)/ vs /(foo)?/

kj <socyl@xxxxxxxxxxxxxxxxx> wrote in comp.lang.perl.misc:
>
>
>
>
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> While looking at someone else's code I came across a regular
> expression that included a construct like /(foo|)/. As far as I
> can tell, it should produce the same result as /(foo)?/. But the
> author of the code knows a heck of a lot more Perl than I do, so
> I'm wondering why she would have picked the former over the latter.
> Any ideas?

The difference is in what is captured when no "foo" is found in the
string. /(foo|)/ matches an empty string, so $1 is an empty string
after the match. /(foo)?/ skips the match entirely, so $1 is undefined.
A subtle but relevant difference.

Anno
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