php获取访客ip地址的方法

<p><?php </p><p> function ip() { </p><p>if(getenv('HTTP_CLIENT_IP') && strcasecmp(getenv('HTTP_CLIENT_IP'), 'unknown')) { </p><p>$ip = getenv('HTTP_CLIENT_IP'); </p><p>} elseif(getenv('HTTP_X_FORWARDED_FOR') && strcasecmp(getenv('HTTP_X_FORWARDED_FOR'), 'unknown')) { </p><p>$ip = getenv('HTTP_X_FORWARDED_FOR');</p><p> } elseif(getenv('REMOTE_ADDR') && strcasecmp(getenv('REMOTE_ADDR'), 'unknown')) { </p><p>$ip = getenv('REMOTE_ADDR'); </p><p>} elseif(isset($_SERVER['REMOTE_ADDR']) && $_SERVER['REMOTE_ADDR'] && strcasecmp($_SERVER['REMOTE_ADDR'], 'unknown')) { </p><p>$ip = $_SERVER['REMOTE_ADDR']; </p><p>} </p><p>return preg_match("/[\d\.]{7,15}/", $ip, $matches) ? $matches[0] : 'unknown'; </p><p>}</p><p>?></p>