Mixing Arrays

Anybody out there that can help me with this one? Have the following form posting arrays to a text file : <form method="post" action="prod.php"> <input type="text" name="prodid[ ]" size="7"> <input type="text" name="proddes[ ]" size="35"> <input type="text" name="prodid[ ]" size="7"> <input type="text" name="proddes[ ]" size="35"> <input type="text" name="prodid[ ]" size="7"> <input type="text" name="proddes[ ]" size="35"> ... and so on <input type="submit" value="Submit"> prodid is the Product ID and proddes is the Product Description On prod.php I have : $data1 = join("%", $prodid); $data2 = join("%", $proddes); $main_data = "$data1" . "$data2"; $fh = fopen("products.txt", "w"); if (!$fh) { die("<br>Failed to open file"); } fwrite($fh, "$main_data"); fclose($fh); this generates the output in the textfile as: 1%2%3%Product One Description%Product Two Description%Product Three Description Question is - how do I get the script to write to the text file so that I have a result that looks like this: 1%Product One Description%2%Product Two Description%3%Product Three Description Any help will be appreciated! - Thanx August Kupke