Regex match iterative grouping

SamCG has asked for the wisdom of the Perl Monks concerning the following question:

Okay, the code:

perl -e "@re='abcdefg'=~/(..)/g;print join ',', @re;"
#prints ab,cd,ef
[download]

but, what if I don't want the position to set to after the last match, but to one character after the beginning of the last match to produce ab,bc,cd,de,ef,fg? I've tried a few strange variants of adding code into the expression to alter the 'abcdefg' midway, but these don't seem to produce the results I want.

perl -e "$_='abcdefg';@re=/(..)(?{reverse;chop;reverse;})/g;print join
+ ',', @re;"
ab,cd,
perl -e "$_='abcdefg';@re=/(..)(?{$_=substr($_,1)})/g;print join ',', 
+@re;"
bc,ef,
[download]

No particular purpose here other than just to wield regexes better, so if there are practical reasons this is ludicrous feel free to tell me.

-----------------
_{s''limp';@p=split '!','n!h!p!';s,m,s,;$s=y;$c=slice @p1;so brutally;d;$n=reverse;$c=$s**$#p;print(''.$c^chop($n))while($c/=$#p)>=1;}

Comment on Regex match iterative grouping Select or Download Code

Replies are listed 'Best First'.
Re: Regex match iterative grouping by Ido (Hermit) on Apr 06, 2006 at 16:35 UTC
Quiet interesting, but: `'abcdefg'=~/(?=(..))/g;` [download] Does the job... Please see: Repeated patterns matching zero length substring	[reply] [d/l]
Re: Regex match iterative grouping by sfink (Deacon) on Apr 06, 2006 at 17:10 UTC
Adjust the quotes for your shell: `perl -le '$_ = "abcd"; while (/(..)/g) { print $1; --pos }'` Or closer to your exact question: `perl -le '$_ = "abcdefg"; while (/(...)/g) { print $1; pos($_) -= leng +th($1); pos($_)++ }'` [download] You might be able to do that in a list-context match with an embedded expression, but that would be too scary for me.	[reply] [d/l] [select]
Re^2: Regex match iterative grouping by SamCG (Hermit) on Apr 06, 2006 at 19:39 UTC
Thank you, both solutions work, though I will have to work on understanding Ido's a bit better. Note that as far as "adjusting my quotes to my shell", that technique doesn't work on my <Windows XP> shell. Inverting them (double-quotes surrounding all executable code, with either single quotes in the middle or escaped double-quotes) does work. ----------------- _{s''limp';@p=split '!','n!h!p!';s,m,s,;$s=y;$c=slice @p1;so brutally;d;$n=reverse;$c=$s**$#p;print(''.$c^chop($n))while($c/=$#p)>=1; =1;}	[reply]