I have a PHP script that sends a user to a homepage called index.php
then redirects them to one of six random homepages. I using this
script to test the effectiveness of different homepages.

Now I want to modify the script, so each user will see the same
version of the homepage they saw when they first visited if they visit
again. From a experience perspective I don't want a returning user to
see a different homepage or they might think they've visited the wrong
site.

I'm assuming that I should set a cookie to do this and place the
cookie code before the code that chooses a random homepage. The
randomizer selects a homepage with a value of 0 to 5, so I figure the
cookie should record this value for each user upon their first visit
to the site. The cookie would override the randomizer if a user visits
the site again.

For example, if a user visits the site they might be redirected to
index5.php. That would mean that the randomizer chose randomtopic 4
which corresponds to index5.php. That user should be redirected to
index5.php as the homepage if they visit again.

Please add the necessary code to the script below. I am not a
programmer, so please show me and explain exactly what I need to do to
get this working.

Thanks!

<?php 

srand((double)microtime()*1000000); 
$randomtopic = rand(0,5); 

if  ($randomtopic ==  "0") {   
header('Location: index1.php);  

} else if ($randomtopic ==  "1") {   
header('Location: index2.php);  

} else if ($randomtopic ==  "2") {   
header('Location: index3.php); 

} else if ($randomtopic ==  "3") {   
header('Location: index4.php);    

} else if ($randomtopic ==  "4") {   
header('Location: index5.php); 

} else if ($randomtopic ==  "5") {   
header('Location: index6.php);    

} else {   
echo ( "ERROR: There was a problem running the script. ");   
}   
?>

<?php
/**
 * Chooses a random page and saves a cookie
 * 
 * returns $randomtopic
 * -OR- FALSE on error
 */
function rand_page() {
	srand((double)microtime()*1000000); 
	$randomtopic = rand(1,6); 
	if(setcookie("MyCookie", $randomtopic)) {
		return $randomtopic;
	} else {
		return FALSE;
	};
};

/**
 * Checks if the cookie is set
 * 
 * returns $page_num
 * -OR- ERROR -AND- Returns random $page_num
 */
if(isset($_COOKIE['MyCookie'])) {
	$page_num = $_COOKIE['MyCookie'];
} else {
	if(!$page_num = rand_page()) {
		echo ("ERROR: There was a problem saving the cookie.\n</ BR>");
		$page_num = rand(1,6);
	};
};

$page_name = 'index'.$page_num.'.php';
header('Location: '.$page_name);  
?>