my $date = "10/13/2006";
if ($date=~/(\d{1})\/(\d{2})\/(\d{4})/) {
    $date="0".$1."\/".$2."\/".$3;
    print "<br>L1 - $date<br>";
    
} elsif ($date=~/(\d{2})\/(\d{1})\/(\d{4})/) {
    $date=$1."\/0".$2."\/".$3;
    print "<br>L2 - $date<br>";
} else {
    $date=~/(\d{1})\/(\d{1})\/(\d{4})/;
    $date="0".$1."\/0".$2."\/".$3;
    # no print here?!?    
}

##</code><code>##

my $date = "10/13/2006";
my ($m,$d,$y)=split m(/), $date;
$date=join '/', (map sprintf('%02d', $_), $m, $d), $y;

##</code><code>##

my $date = "10/13/2006";
$date=sprintf '%02d/%02d/%d', split m(/), $date;