EDIT:

Well I feel silly. As AnomalousMonk below mentioned, I had (unintentionally) provided the same solution as Athanasius did earlier. I could have sworn Athanasius' solution involved reading in the file all into an array before processing. That is what I get for not reading all the replies carefully I suppose.

Original reply spoilr'd to avoid polluting the thread with redundant bits (Unless there is a "Delete Post" gubbin I somehow missed?)