So: is what you want to do to count the number of (non-epoch) lines in the earlier file that are before the first date in the second file?
Note that unless the first timestamp in the later file exactly matches one of the timestamps in the earlier file, your code will keep counting through the rest of the file.
Use the 3-arg form with lexical filehandles:
open my $fh, '<', 'newfile.txt'
or die "Can't open newfile.txt: $!\n";
If use warnings
was in scope where you reference @Array0
, you would have seen a warning (not that it affects the correct execution of your code).