push(my @contentsOfDataBase, $_);

That's where you are masking an earlier declaration. Just remove the my.

while ($boxEnd >= my $boxBegining, $boxBegining++)

And that's where you are using >= in void context. That should probably look something like ...

my $boxBegining; 
while ($boxEnd >= $boxBegining) { 
    $boxBegining++; 
    # ... and the rest of your loop ...  
}
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