Yet another way. Pre-5.10 compatible; avoids explicit captures. Unfortunately, rather heavy on the look-arounds. 

c:\@Work\Perl\monks>perl -wMstrict -MData::Dump -le
"my $s = qq{a aa 21a a 123 a b9 b bb aa1 1aa @ARGV};
 dd $s;
 ;;
 my @captures = $s =~ m{
   \b \d+ (?= (?: a|b) \b)
   |
   (?<= \b (?: a|b)) \d+ \b
   |
   \b (?: a|b) (?= \d)
   |
   (?<= \d) (?: a|b) \b
   }xmsg;
 dd \@captures;
"  "aa11 11aa [b42] (12a)"
"a aa 21a a 123 a b9 b bb aa1 1aa aa11 11aa [b42] (12a)"

[21, "a", "b", 9, "b", 42, 12, "a"]

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Give a man a fish:  <%-{-{-{-<

In reply to Re: Complex regex question by AnomalousMonk
in thread Complex regex question by Cody Fendant

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