php获取客户端ip

/**

* 获取客户端IP地址

* @return ip地址

*/

function get_ip() {

static $ip = NULL;

if ($ip !== NULL) return $ip;

if (isset($_SERVER[HTTP_X_FORWARDED_FOR])) {

$arr = explode(,, $_SERVER[HTTP_X_FORWARDED_FOR]);

$pos = array_search(unknown,$arr);

if(false !== $pos) unset($arr[$pos]);

$ip = trim($arr[0]);

}elseif (isset($_SERVER[HTTP_CLIENT_IP])) {

$ip = $_SERVER[HTTP_CLIENT_IP];

}elseif (isset($_SERVER[REMOTE_ADDR])) {

$ip = $_SERVER[REMOTE_ADDR];

}

return $ip;

}