Just as a side note, this: 

my @bl = <QA>;
my @a = <FA>;
my %h;

@h{@bl} = @bl;

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is a relatively poor way of using memory: loading the file into an array to immediately store it into a hash and no longer use the array is not very efficient. I would rather iterate on the file and load directly into the hash. Something like this: 
my %h;
while (<QA>) {
     $h{$_) = 1;
}

[download]
Or possibly: 
%h = map {$_, 1} <QA>;

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although this: 
 %h = map { chomp $_; $_, 1}  <QA>;

[download]
might be better.

In reply to Re: get difference of two arrays by Laurent_R
in thread get difference of two arrays by naturalsciences

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