adding GET variables to a header() location in a page template

Question

header('Location: /page-name/?var1=' 
. $_GET['var1'] . '&var2=' . $_GET['var2'] );
exit();

The result of the above code ends up redirecting the site to:

http://www.domain.com/page-name/?var1=val1&var2=val2`

I have a feeling Wordpress is cleaning the ampersand in the URL, but I don't at what point it would do that...

Edit: With Milo's direction, I modified the redirect code to look like this and it started working properly.

$url = '/page-name/';
$args =  array('var1'=>$_GET['var1'], 'var2' => $_GET['var2']);
$url = add_query_arg($args, $url);
wp_redirect($url);
exit();

I'd still like to know why the ampersand got converted to HTML in the first place.

Answer 1

WordPress has API functions for doing both of these things- wp_redirect and add_query_arg.