Redirect visitor based on referral URL - php

Question

I want to redirect visitors to one page on my website if they have come from a certain URL and another if they don't.
<?
$referer = $_SERVER['HTTP_REFERER'];
if ( $referer != "http://URL1" ) {
header('Location: page1');
exit;
} else {
header('Location: page2');
}
?>
Whatever referrer I come to the page on it goes to page 1 and never to page 2. I have used this code in a index.php file so its the first page the visitor is directed too.

Answer 1

UPDATE: alright, so from the discussions, it seems that the reason why your code won't work is that you are checking the referer string using the "now-www" url, while the actual referer string has "www" in the url. Please, make sure to use the exact referer string. Otherwise, if you are redirecting based on the hostname of the referer you can use the updated answer below.
<?php
$referer = str_replace("www.", "", parse_url($_SERVER['HTTP_REFERER'], PHP_URL_HOST));
switch($referer) {
case "johnchow.com":
header("Location: page1");
break;
case "domain2.com":
header("Location: page2");
break;
default:
header("Location: page3");
}
exit;

Answer 2

For starters change this to
if ( $referer != "http://URL1" || $referer != "http://URL2" )
Secondly, page1 and page2 are likely giving the error because they are invalid. Include the path and extension. For example:
header('Location: http://www.yourlocation/page1.php')
Looks like the error has been clarified...