php获取访问的ip

function getip(){
    if(isset($_SERVER['HTTP_X_FORWARDED_FOR'])){
        $online_ip = $_SERVER['HTTP_X_FORWARDED_FOR'];
    }elseif(isset($_SERVER['HTTP_CLIENT_IP'])){
        $online_ip = $_SERVER['HTTP_CLIENT_IP'];
    }else{
        $online_ip = $_SERVER['REMOTE_ADDR'];
    }
    return $online_ip;
}