WordPress posts order by modified date

WordPress posts order by modified date

<?php
function modified( $query )
{
    if ( $query->is_main_query() && ( $query->is_home() || $query->is_search() || $query->is_archive() )  )
    {
        $query->set( 'orderby', 'modified' );
        $query->set( 'order', 'desc' );
    }
}
add_action( 'pre_get_posts', 'modified' );

?>