[Tcl-bugs] [ tcl-Bugs-1513763 ] The result of regexp is abnormal

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Bugs item #1513763, was opened at 2006-06-27 22:20
Message generated for change (Comment added) made by dkf
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Category: 42. Regexp
Group: current: 8.4.13
Status: Pending
Resolution: Works For Me
Priority: 5
Submitted By: Nobody/Anonymous (nobody)
Assigned to: Pavel Goran (pvgoran)
Summary: The result of regexp is abnormal

Initial Comment:
When I use regexp {^(oo+?)(\1)*$} to verify a number 
is prime or not. The result was abnormal.

I use another script like perl, python ...
It does work.

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Comment By: Donal K. Fellows (dkf)
Date: 2006-06-28 01:45

Message:
Logged In: YES 
user_id=79902

I've no idea what the above regular expression is trying to
achieve, since it will match any non-empty sequence of 'o'
characters (the * allows bits to be ignored). However, if I use:
   ^(oo+?)\1+$
as the RE (dropping one set of parens for simplicity and
changing to using a +) then I get a perfectly adequate
non-prime detector.
   % info patch
   8.4.7
   % #Print the lowest prime factor of 169...
   % string length [lindex [regexp -inline {^(oo+?)\1+$}
[string repeat o 169]] 1]
   13

Looks like pilot error to me.

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