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Re: Lookahead regex help

by borisz (Canon)
on Aug 16, 2004 at 16:24 UTC ( #383358=note: print w/replies, xml ) Need Help??

in reply to Lookahead regex help

Im not really sure if this is what you have in mind:
my $string = 'aaabbcddeef'; while($string =~ m/((.)\2*)/gi) { print "$1\n"; } __OUTPUT__ aaa bb c dd ee f

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Re^2: Lookahead regex help
by debiandude (Scribe) on Aug 16, 2004 at 16:34 UTC
    That seems to work. Thanks. But I am curious as to what the \2 does?
      \2 looks for what the second () pair has captured. In this case a single char.
      $$ perl -MYAPE::Regex::Explain -e'die YAPE::Regex::Explain->new(qr/((. +)\2*)/i)->explain' The regular expression: (?i-msx:((.)\2*)) matches as follows: NODE EXPLANATION ---------------------------------------------------------------------- (?i-msx: group, but do not capture (case-insensitive) (with ^ and $ matching normally) (with . not matching \n) (matching whitespace and # normally): ---------------------------------------------------------------------- ( group and capture to \1: ---------------------------------------------------------------------- ( group and capture to \2: ---------------------------------------------------------------------- . any character except \n ---------------------------------------------------------------------- ) end of \2 ---------------------------------------------------------------------- \2* what was matched by capture \2 (0 or more times (matching the most amount possible)) ---------------------------------------------------------------------- ) end of \1 ---------------------------------------------------------------------- ) end of grouping ----------------------------------------------------------------------

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