$a = 1990;
$b = 3;
$c = 2;

list($a, $b, $c) = explode('-', '1990-03-02');

$dateString = "1990-03-02";
list($a, $b, $c) = sscanf($dateString, "%d-%d-%d");

$str = "1990-03-02";
$a = explode('-', $str);
$year = $a[0];
if($a[1][0]==0){$month = $a[1][1];}else{$month = $a[1];}
if($a[2][0]==0){$day = $a[2][1];}else{$day = $a[2];}

$str = "1990-03-02";
$a = explode('-', $str);
$year = $a[0];
$a[1][0]==0 ? $month = $a[1][1] : $month = $a[1];
$a[2][0]==0 ? $day = $a[2][1] : $day = $a[2];

$d = DateTime::createFromFormat('Y-m-d', '1990-03-02');

$a = (int)$d->format('Y');
$b = (int)$d->format('j');
$c = (int)$d->format('n');

$week = (int)$d->format('W');

$new_date = $d->add(new DateInterval('P1W'));