Find visitor ip address

To find IP address of visitor, use following code.

function get_visitor_ip() {
   //Regular expression pattern for a valid IP address
   $ip_regexp = "/^([0-9]{1,3})\.([0-9]{1,3})\.([0-9]{1,3})\.([0-9]{1,3})/";

   //Retrieve IP address from which the user is viewing the current page
   if (isset ($HTTP_SERVER_VARS["HTTP_X_FORWARDED_FOR"]) && !empty ($HTTP_SERVER_VARS["HTTP_X_FORWARDED_FOR"])) {
      $visitorIP = (!empty ($HTTP_SERVER_VARS["HTTP_X_FORWARDED_FOR"])) ? $HTTP_SERVER_VARS["HTTP_X_FORWARDED_FOR"] : ((!empty ($HTTP_ENV_VARS['HTTP_X_FORWARDED_FOR'])) ? $HTTP_ENV_VARS['HTTP_X_FORWARDED_FOR'] : @ getenv ('HTTP_X_FORWARDED_FOR'));
   } else {
      $visitorIP = (!empty ($HTTP_SERVER_VARS['REMOTE_ADDR'])) ? $HTTP_SERVER_VARS['REMOTE_ADDR'] : ((!empty ($HTTP_ENV_VARS['REMOTE_ADDR'])) ? $HTTP_ENV_VARS['REMOTE_ADDR'] : @ getenv ('REMOTE_ADDR'));
   }

   return $visitorIP;
}