Return current date plus 7 days

$now = date('Y-m-d');
$start_date = strtotime($now);
$end_date = strtotime("+7 day", $start_date);
echo date('Y-m-d', $start_date) . '  + 7 days =  ' . date('Y-m-d', $end_date);

strtotime will automatically use the current unix timestamp to base your string annotation off of.

Just do:

$date = strtotime("+7 day");
echo date('M d, Y', $date);

Added Info For Future Visitors: If you need to pass a timestamp to the function, the below will work.

This will calculate 7 days from yesterday:

$timestamp = time()-86400;

$date = strtotime("+7 day", $timestamp);
echo date('M d, Y', $date);

If it's 7 days from now that you're looking for, just put:

$date = strtotime("+7 day", time());
echo date('M d, Y', $date);

$date = new DateTime(date("Y-m-d"));
$date->modify('+7 day');
$tomorrowDATE = $date->format('Y-m-d');