getting the right line from flat file

[zzz]

I have two flat files. When a user logs in I pass values of the first file with the server eg.

<? print $_SESSION['value1']; ?>

.

Both of the files have the same identifier, let's say value1.How would I get a field result from file #2 where value1==x when the file #1 has value1==x . I know how to do that when I use db, but not sure how when I deal with flat files...

Here's how I try it now, but apparently it doesn't work:

if (!isset($value1)) { // <- this value1 comes with session from file#1 and it is identical  to value1 in file#2
		 	$file=file("myfile");
			@list($value1, $value2, $value3)=explode("<del>", $file[$value1]);
			echo $value3;
		 }