Thank you so much guys. I didn't notice I got such many helps here. ;)

Just share, I got another working regex from perlguru, I changed \d to \w.

$line =~ s/(\w{3}(?!$))/$1-/xg;

[download]

By the way, is there a major processing speed to concern since there are more than one regex to get the same results?

such as: 
$string =~ s/(\w\w\w)(?!$)/$1-/g;
from McA

s/(\w{3})\B/$1-/g
from Ken

[download]

In reply to Re: Regex split string into n-length by hankcoder
in thread Regex split string into n-length by hankcoder

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