my ($y, $m, $d) = unpack('a4a2a2', $str);

##</code><code>##

my $y = substr($str, 0, 4);
my $m = substr($str, 4, 2);
my $d = substr($str, 6, 2);

##</code><code>##

my ($y, $m, $d) = $str =~ /(.{4})(.{2})(.{2})/;

##</code><code>##

$str =~ /(.{4})/g;  my $y = $1;
$str =~ /(.{2})/g;  my $m = $1;
$str =~ /(.{2})/g;  my $d = $1;

##</code><code>##

my ($y, $m, $d) = map { 0+$_ } unpack('a4a2a2', $str);

##</code><code>##

printf("%04d/%02d/%02d\n", $y, $m, $d);

##</code><code>##

$formatted = sprintf("%04d/%02d/%02d", $y, $m, $d);