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Re: Regexp problem

by agaved (Novice)
on Aug 28, 2012 at 20:15 UTC ( [id://990323]=note: print w/replies, xml ) Need Help??


in reply to Regexp problem

Thanks for the quick answers

I was watching this on the debugger and I think I misinterpreted it.

So now my question is: why in the debugger I get

x "24-06" =~ /\d{2}-\d{2}/ as 1,

but x "24-06" =~ /\d{2}-\d{2}(p)*/ as undef?

Replies are listed 'Best First'.
Re^2: Regexp problem
by linuxer (Curate) on Aug 28, 2012 at 20:35 UTC

    As far as I understand the debugger, both expressions are evaluated in list context.

    The first expression simply returns 1 for success and I assume 0 an empty list for failure; so it's a single boolean result in list context.

    The second expression has capturing parantheses, which (in list context) produces a list of captured results. As your (p)* could not be matched, there is no captured value for (p), so it returns a list with one element: undef.

    That's my attempt to explain it. I am sure there are others who can explain it more detailed and accurately and even show some insight into the internals ...

      DB<4> x "24-06" =~ /\d+-\d+/ 
0  1
  DB<5> x "24-06" =~ /\d+-\d+failure/
  empty array

    [download]

    edit:

    • fixed assumption upon failed regex match, added code example, some rephrasing
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