写入文本文件txt的PHP代码

$ip = $_SERVER["REMOTE_ADDR"];
$time = date("Y-m-d H:i:s", time());
$from = '';
if(isset($_SERVER['HTTP_REFERER']))
{
   $from = $_SERVER['HTTP_REFERER'];
}
$myfile = 'wtndata/statistic.txt';
$str = "ip='".$ip."' from='".$from."' time='".$time."'rn";
$file_pointer = fopen($myfile,"a");
fwrite($file_pointer,$str);
fclose($file_pointer);