IP store in a File

keep IP  from visitors and place them on a file.

<?php
$file = fopen("ip.txt","a");
$ip=$_SERVER['REMOTE_ADDR'];
echo fwrite($file,$ip);
fclose($file);
?> 

this store in a file as name ip.txt

("ip.txt","a"); 
the second parameter can use "w" if you want only write mode 
"a" stands for append mode .