add acf field in contact forms 7

function cf7_add_post_id(){

    global $post;
    //$enddate=get_field(end_date,$post->ID);
    $startdate=get_field(start_date,$post->ID);
    $sdate=date("d.m.Y",strtotime($startdate));
    return $sdate;

}

add_shortcode('CF7_ADD_POST_ID', 'cf7_add_post_id');