echoing a sum

[Anon]

I am tyring to do something I thought would be trivial, but I am not having any luck. I have some next/prev links at the bottom of a page. If the current id is 5 the next-link would be file.php?id=6 ($id+1), and prev-link would be file.php?id=4 ($id-1).

How can I print out the sum of $id+1 or $id-1, without changing the value of $id, or assigning a temp var.

Thanks.

[Anon]

Nevermind, it was trivial. I just wasn't saving my file changes. :p

echo "<a href='$PHP_SELF?p=".($p+1)."'>Next</a>";