= 16 && $b <= 31) ||
           ($a == 192 && $b == 168);
  }   
   
  function getIP() {
    $default = false;
    
    if (isset($_SERVER)) {
      $default_ip = $_SERVER["REMOTE_ADDR"];      
      $xforwarded_ip = $_SERVER["HTTP_X_FORWARDED_FOR"];
      $client_ip = $_SERVER["HTTP_CLIENT_IP"];    
    } else {
      $default_ip = getenv('REMOTE_ADDR');
      $xforwarded_ip = getenv('HTTP_X_FORWARDED_FOR');
      $client_ip = getenv('HTTP_CLIENT_IP');
    }
    
    if ($xforwarded_ip != "") {
      $result = $xforwarded_ip;
    } else if ($client_ip != "") {
      $result = $client_ip;
    } else {
      $default = true;
    }
    
    if (!$default) { // additional check for private ip numbers 
      $default = isPrivateIP($result);
    }
    
    if ($default) {
      $result = $default_ip;
    }
    
    return $result;
  }
  
  function showUSContent() {
    // show US content here, for ex. Yahoo! ads  
  }
  
  function showInternationalContent() {
    // show international content here, for ex. Google ads
  }
  
  function showGeoTargetContent() {
    // make a valid request to the hostip.info API  
    $url = "http://api.hostip.info/country.php?ip=".getIP();
  
    // fetch with curl
    $ch = curl_init();
  
    curl_setopt($ch, CURLOPT_URL, $url);
    curl_setopt($ch, CURLOPT_HEADER, 0);
    curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
    $country = curl_exec($ch);
  
    curl_close ($ch);
  
    // display according geotarget
    if ($country == "US") {
      showUSContent();
    } else {   
      showInternationalContent();
    }
  }  

  showGeoTargetContent();
?>