AutoRegexBenchmark

use Benchmark qw/cmpthese/;
use Data::Dumper;

my @set= qw (123456  677  233  10000  11000  30  1  200
                      120007  12  350  440  55 55  84213  999999
                      300000  1000000  2500000  400000000
                      22  0  1000  82468  7305 5  880000  10002000
                      111  8990  578901  9999999  7777);

cmpthese(-10,{
  regex2=> sub {
      grep { /\b\d{1,6}\b/g}  @set ;
  },
  regex1=> sub {
          grep { /(?<= )\w\w?+\w?+\w?+\w?+\w?+(?= )|123456/g}  @set ;
  }
});