The first place to go is `man perlre`: you should get rid of all these [ and ] characters when they're redundant..

for( qw{
   2312112
   abc-erte
} ){
   print "$_ ",
      m<^(?:
        \d{5,8}  #5 to 8 digits
           |     # OR
        \w{3}    # 3 alpha chars 
                 # (maybe you want to replace \w)
        -        # one hyphen
        .{4}     # 4 chars
      )$>x
     ? 'matches' : 'doesn\'t match', "\n";
}
[download]

update: typos at end of regexp

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