I suspect the other posts will help you with your problem, but in the event they don't, it seems like you're omitting or heavily editing your code. What you posted shouldn't even compile, as you have variables that are undeclared. Typically you only get that message when working with an undefined scalar in such a way that you're assuming it has content. This can occur with your array if you have an undefined element, which is likely because you are pushing $line onto it, and I don't see anywhere where you are setting $line. So basically for each line that you read from the file (into $_), you're pushing 'undef' onto the array. Another poster mentioned that you should be using $_, which is correct, or change your while construct to read something like: while ($line = <FILE>) { ....

So if these posts don't help you, can you post the real code with 2 or 3 additional lines so that we can get a better feel for context? Good luck.