c:\@Work\Perl\monks>perl -wMstrict -MData::Dump -le "my @nums = ('1203', '1204', '1207'); my $regex = '\b(?:' . join('|', @nums) . ')\b'; print qq{'$regex'}; ;; my @matches = 'w 1207 x 1203 y 9999 z' =~ m{ $regex }xmsg; dd \@matches; " '\b(?:1203|1204|1207)\b' [1207, 1203]