http://www.perlmonks.org?node_id=1004810


in reply to rotate a vector with a regex?

... move it pairwise along the string (bubble it).

As I understand it, this won't work because substitution is not being done on the original string during the actual substitution process; rather, an intermediate string is being built up during this process, and the intermediate string is copied to the original string when the process is complete.

That's why something like
    ($x = $y) =~ s{foo}{bar}xms;
works as it does: instead of copying the intermediate back to the original string ($y), it's copied to another string ($x) leaving the original string untouched. (Or maybe $x is just used as the 'intermediate' in the first place. Whatever...)

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Re^2: rotate a vector with a regex?
by LanX (Saint) on Nov 21, 2012 at 17:29 UTC
    > rather, an intermediate string is being built up during this process, and the intermediate string is copied to the original string

    I think you're right

      DB<123> $x=join "",a..j
 => "abcdefghij"
 
  DB<124> $x =~ s/(.)(?=(.))/$2$1/g
 => 9
 
  DB<125> $x
 => "bacbdcedfegfhgihjij"

    [download]

    Cheers Rolf

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