Ikegami, I am curious if you can replicate my results with the substr idea plugged into your benchmark code? Update: the reason I ask is that I know you have a very fast 64 bit machine and there could be some differences between my much slower, older 32 bit machine. 
use strict;
use warnings;

use Benchmark qw(:all);

print("This is Perl $]\n");

my %tests = (
    repeat => 'my ($y,$m,$d) = $date =~ /(\\d\\d\\d\\d)(\\d\\d)(\\d\\d
+)/;',
    range  => 'my ($y,$m,$d) = $date =~ /(\\d{4})(\\d{2})(\\d{2})/;',
    isook  => 'my ($y,$m,$d) = $date =~ /(....)(..)(..)/s;',
    unpack => 'my ($y,$m,$d) = unpack "A4 A2 A2", $date;',
    substr => 'my $y = substr($date,0,4);my $m = substr($date,4,2);my 
+$d = substr($date,6,2);'
);

# These don't result in any opcodes.
$_ = 'use strict; use warnings; our $date; '.$_
    for values(%tests);

our $date = '20091202';

my $results = cmpthese(-3, \%tests);
__END__
This is Perl 5.010000
            Rate  range  isook repeat unpack substr
range   151695/s     --    -7%    -8%   -54%   -85%
isook   162964/s     7%     --    -1%   -50%   -84%
repeat  165314/s     9%     1%     --   -49%   -84%
unpack  326977/s   116%   101%    98%     --   -68%
substr 1010101/s   566%   520%   511%   209%     --

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In reply to Re^4: better (faster) way of writing regexp by Marshall
in thread better (faster) way of writing regexp by jodaka

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