Re^4: A regex that only matches at offset that are multiples of a given N?

Because with it, it only matches the first match; not any second or subsequent properly aligned matches?:

print "$-[0]: $1" while $a =~ m[(?:.{4})*(?=(aa..))]g;;
0: aawx
404: aawx
405: aadz
481: aadz

print "$-[0]: $1" while $a =~ m[^(?:.{4})*(?=(aa..))]g;;
0: aawx

print "$-[0]: $1" while $a =~ m[(?:.{4})*(?=(gg..))]g;;
0: gghn
208: gghn
211: ggyj
955: ggyj

print "$-[0]: $1" while $a =~ m[^(?:.{4})*(?=(gg..))]g;;
0: gghn
[download]

With the rise and rise of 'Social' network sites: 'Computers are making people easier to use everyday'

Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error.

"Science is about questioning the status quo. Questioning authority".

In the absence of evidence, opinion is indistinguishable from prejudice.

Comment on Re^4: A regex that only matches at offset that are multiples of a given N? Download Code