This demonstrates the (a?) difference. How you interprete the results relative to the descriptions I can't quite figure.
perl> $s = join'','a'..'z'
perl> 1 while $s =~ m[((.).)(?{ print "$^N:$+\n"; })]g
ab:a
cd:c
ef:e
gh:g
ij:i
kl:k
mn:m
op:o
qr:q
st:s
uv:u
wx:w
yz:y
perl> 1 while $s =~ m[((..).)(?{ print "$^N:$+\n"; })]g
abc:ab
def:de
ghi:gh
jkl:jk
mno:mn
pqr:pq
stu:st
vwx:vw
One interesting difference in the description that had me salivating breifly was that $+ is explicity defined read-only whereas (in your snippet) $^N it's not but whilst attempting to assign to it doesn't result in an error, it also has no effect on the bound string.
Examine what is said, not who speaks.
1) When a distinguished but elderly scientist states that something is possible, he is almost certainly right. When he states that something is impossible, he is very probably wrong.
2) The only way of discovering the limits of the possible is to venture a little way past them into the impossible
3) Any sufficiently advanced technology is indistinguishable from magic.
Arthur C. Clarke.
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