How to add a body class to all interior pages except the homepage

I want to add a class to the body tag to all pages EXCEPT the homepage. Right now I have.

<?php body_class('interior'); ?>

But it adds ‘interior’ to ALL pages including the home page.

What is the best standard way of adding a class to the body tag?

Try it:

<?php
$class = ! is_home() ? "interior" : "";
body_class( $class );
?>

Or this:

<?php
body_class( ! is_home() ? "interior" : "" );
?>