in reply to Re^2: substrings that consist of repeating characters
in thread substrings that consist of repeating characters

you might want to run the different variants thru use re "debug" to see how they are translated into regex primitives. This might give you a clue what is happening.

Cheers Rolf
(addicted to the Perl Programming Language :)
Wikisyntax for the Monastery

In Section Seekers of Perl Wisdom