$total is the number of elements in @lines, not the last array index. You're looping until $i <= $total, so the last element that you're trying to access is beyond the bounds of the array. So it's undefined.

Say that your array has 5 elements: 

my @lines = qw/a b c d e/;
my $total = @lines;

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$total is now 5, but the last array index is 4, because the indices start at 0. In your for loop, $i goes from 0 to 5, and when $i is 5, you're trying to access 
$lines[5]

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which doesn't exist.

The solution, of course, is to change your for loop: 

for my $i (0..$total-1) {
...

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Of course, if this is all you're doing, you may as well just use grep: 
my $total = grep $_ ne "\n", @lines;

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In reply to Re: I don't understand why I'm getting an unitialized value warning by btrott
in thread I don't understand why I'm getting an unitialized value warning by little_mistress

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