Thank you for your very nice article, I certainly learned some new tricks!

Just one little comment: The code in the last paragraph did not work because by default regular expressions are greedy. (Did this change with the Perl versions in between?) The only right-substring that comes out is the full string: 

$_ = "Hello";
print "$1\n" while /(?=(.*))/g;

[download]
Output: 
Hello

[download]
Making the "(.*)" part non-greedy fixes it (in Perl 5.10): 
$_ = "Hello";
print "$1\n" while /(?=(.*)?)/g;

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Output: 
Hello
ello
llo
lo
o

[download]

In reply to Re: Using Look-ahead and Look-behind by jds17
in thread Using Look-ahead and Look-behind by Roy Johnson

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