thinkphp How to get the client ip_php tips

In the thinkphp framework, the system has a built-in GET_CLIENT_IP method for obtaining the IP address of the client, using the example:
$ip = Get_client_ip ();
In addition to thinkphp built-in GET_CLIENT_IP functions, you can use the following function to obtain the client IP address.
$type indicates return type 0 return IP address, 1 return IPV4 address number
share the code as follows

function get_client_ip ($type = 0) {
  $type    = $type? 1:0;
  Static $IP =  NULL;
  if ($ip!== NULL) return $ip [$type];
  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 '];
  }
  IP Address legal authentication
  $long = Ip2long ($IP);
  $ip  = $long? Array ($ip, $long): Array (' 0.0.0.0 ', 0);
  return $ip [$type];

I hope this article is helpful for you to learn PHP program design in depth.