JAWTDI:

#!/usr/local/bin/perl -l -w

use strict;
my $str = "aabbcc";
my @arr = unpack("A2" x (length($str)/2), $str);
# Or marginally better
#my @arr = unpack("A2" x (length($str) >> 1), $str);
print for @arr;
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Neither of these is significantly better than using a regex, though.