how to empty the broswer's cache or reset a:visited?

hi,
anyone knows how to empty the browser cache of a user?
so when he surf the site another time the visited links will be reset to zero?
iv found this piece of code, but i dont know where to put it

<?php
session_start();

$_SESSION = array();
session_destroy();
?>

i wrote it in a new snippet and i called the snippet in the head section
but i think that i have a mistake cuz its not working
thanks

You aren’t supposed to meddle with the user’s browser. The session has nothing to do with the user’s browser cache; all it does is set a cookie, which is another matter altogether.

You can style the visited links to be the same as fresh links or set the no-cache parameter:
http://www.htmlgoodies.com/beyond/reference/article.php/3472881

ok, thanks for the replies guys

Just an interesting side note on the subject of a:visited; since it’s possible for sites to determine where you’ve been by using a background image for a:visited and supplying a hidden (long) list of links, I’ve taken advantage of a Firefox hack to turn off the storing of visited links altogether.

i have read the following article http://www.htmlgoodies.com/beyond/reference/article.php/3472881
but its not working at all
I’m gonna try to find a solution with JavaScript.

That’s because the page-visited list is different than the browser cache, it’s the history file. Unless the user clears his history it can stay for months.