Problem logging users out - php

Question

I use the following codes to log users out from a web app. while logging in I set cookie email and password, but after logging out, visiting the home page automatically logs the user in again, probably because the cookie wasn't successfully destroyed. Please how do I get it right. Here is log out code
function log_out() {
$old_user = $_SESSION['valid_user'];
unset($_SESSION['valid_user']);
unset($_SESSION['login']);
unset($_SESSION['blog_addr']);
$result_dest = session_destroy();
setcookie('email', '');
setcookie('pswd', '');
if (!empty($old_user))
if ($result_dest)
return true;
else
$msg = 'Could not log you out ';
else
$msg = 'You have not been logged in so you are not logged out ';
return $msg;
}///:~

Answer 1

You need to set setcookie to an expiration date in the past. See the example here:
http://php.net/manual/en/function.setcookie.php

Answer 2

Try setting the cookie expiration for some time in the past:
setcookie ("email", "", time() - 3600);

Answer 3

How did you set up your cookie? ( logging in ).
In general setting a cookie off , you have to go back in time !
setcookie("email", "",time()-3600,'/');

Answer 4

In addition to other comments. You've set $_SESSION['valid_user']; to $old_user before you did an unset, so you should't be checking for $old_user as it contains the old data. you should't even need to set those to any variables. Also you should be using brackets.
function log_out() {
unset($_SESSION['valid_user']);
unset($_SESSION['login']);
unset($_SESSION['blog_addr']);
session_destroy();
setcookie('email', '', time() - 3600);
setcookie('pswd', '', time() - 3600);
if (!isset($_SESSION['valid_user'])){
if ($result_dest) // don't know what this does.
return true;
else
$msg = 'Could not log you out ';
}
else
$msg = 'You have not been logged in so you are not logged out ';
return $msg;
}

Answer 5

Try to delete the cookies by doing this:
setcookie ("email", "", time() - 3600);
setcookie ("pswd", "", time() - 3600);
This will delete the cookies by setting their expiration date in the past.