use strict;
use warnings;

use File::Find;
use Data::Dumper;

my %addresses;

sub test1 {
    my ($from);
    find(sub {
        return unless -f $_;

        open my $fh, '<', $_ or die;
            local $/ = '';      # "Paragraph" mode, reads a block of text to next \n\n
            $_ = <$fh>;         # Read Header block

            ($from)= $_ =~ /^From:(.*)/m; # /m to anchor
            #print "$from\n";

        close $fh;
    }, glob('./009_mailtest/*'));

    #print Dumper \%addresses;

}
sub test2{
    binmode(STDOUT,":utf8");
    my ($from,$bgn,$end,$len);

    find(sub {
        return unless -f $_;

        open my $fh, '<:utf8', $_ or die;
            local $/ = '';      # "Paragraph" mode, reads a block of text to next \n\n
            $_ = <$fh>;         # Read Header block

            $bgn=index($_,"From:",0) + length("From:");
            $end=index($_,chr(10),$bgn+1);
            $len=$end - $bgn;
            $from=substr($_, $bgn, $len);
            #print "$from\n";
        close $fh;
    }, glob('./009_mailtest/*'));
}

my($start,$end);
$start=(times)[0];
&test1;
$end=(times)[0];
print "with regex=" . ($end - $start) . "sec\n";

$start=(times)[0];
&test2;
$end=(times)[0];
print "without regex=" . ($end - $start) . "sec\n";