Add Classes for Custom Post Types

// Adds classes for custom post types to body_class() and post_class()
function fb_add_body_class( $class ) {
    $post_type = 'my_example_post_type'; // the Post Type

    if ( get_query_var('post_type') === $post_type ) { // only, if post type is active
        $class[] = $post_type;
        $class[] = 'type-' . $post_type;
    }

    return $class;
}
add_filter( 'body_class', 'fb_add_body_class' );

or

add_filter( 'post_class', 'fb_add_body_class' );
Example: <div <?php post_class('class-name'); ?>>