Show all product titles

add_filter('the_content', 'sw_the_content');
function sw_the_content($content)
{

    if (isset($_GET['show_all_products'])) {
        $query_args = array(
            'post_type' => 'product',
            'posts_per_page' => -1,
            'orderby' => 'title',
            'order'   => 'ASC',
        );

        // The Query
        $the_query = new WP_Query($query_args);

        // The Loop
        if ($the_query->have_posts()) {
            while ($the_query->have_posts()) {
                $the_query->the_post();
                echo the_title();
                echo '<br>';
            }
            /* Restore original Post Data */
            wp_reset_postdata();
        } else {
            // no posts found
        }
    }
    return $content;
}