/**
 * 获取访问用户ip
 */
function get_ip(){
    if(!empty($_SERVER['HTTP_CLIENT_IP'])){
        $ip=$_SERVER['HTTP_CLIENT_IP'];
    }elseif(!empty($_SERVER['HTTP_X_FORWARDED_FOR'])){
        $ip=$_SERVER['HTTP_X_FORWARDED_FOR'];
    }else{
        $ip=$_SERVER['REMOTE_ADDR'];
    }
    return $ip;
}