Passing an Array in HTML

I am reading a file into an array ($data_old = file("config.old");) and then processing it as I receive information from the user. As we all know, the Internet is stateless, so I need to read back in the array after I get my answer. Array definitions are $data_old = array(); $data_new = array(); $data_count = 0; The output code is echo "<P><input type='hidden' name='data_old' value='".$data_old."'>"; echo "<P><input type='hidden' name='data_old' value='".$data_new."'>"; echo "<P><input type='hidden' name='data_count' value=".$data_count.">"; and the input code is $data_old = $_REQUEST['data_old']; $data_new = $_REQUEST['data_new']; $data_count = $_REQUEST['data_count']; $data_count is working so I am assuming my problem is the way that I am passing the array. How can I pass an array or is it not possible? I would think that anything can be passed as it is just bits of data (pun intended). So what goes out should come in. But, for some reason, that is not happening. Any help, suggestions, and guidance is appreciated. Mike