【待望】PerlユーザのためのPHP入門

$i = 90;

$year = date("Y", time());
$day = date("n", time());
$month = date("j", time());
$hour = date("G", time());
$minute = date("i", time());
$second = date("s", time());

$timestamp = mktime($hour, $minute, $second, $month, $day + $i, $year);

print date("Y/n/j G:i:s", $timestamp);

まぁ別に変数を使う必要も無いわけだが。