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... I am not sure what I need to do to get around these. ... I need them to be global variables, so I define them outside of the WHILE loops. If you say that you see them as redundant can you tell me how to get around doing this?

Please understand that what I see as redundant is useless explicit initialization of a variable. In the case of
    my $input_file = undef;
the assignment does exactly what is done by default; it is purely redundant.

Semantically erroneous statements like
    my @files = undef;
are redundant in the present circumstances because the very next thing you do with these arrays (as far as I can see) is to assign them valid data, thus undoing the erroneous initialization. In other circumstances, the erroneous initialization may lead to a nasty bug.

... I need them to be global variables, so I define them outside of the WHILE loops.

Of course, you need to define lexical variables where you need to use them. On this note, you only use the  @dt lexical within the scope of the  if($firstline==1){ ... } statement block, so that's exactly where I would define it:

if($firstline==1){ ... my @dt = $header[0] =~ /(\d+)/g; ... } else { <IN> for 1..1 }
(Incidentally, the  <IN> for 1..1 statement is needlessly involved: if you just want to read and discard one line, the simple  <IN>; statement does the trick.)

Give a man a fish:  <%-{-{-{-<

In reply to Re^3: What can I do to improve my code - I'm a beginner by AnomalousMonk
in thread What can I do to improve my code - I'm a beginner by Anonymous Monk

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