in reply to Strange undefined scalars in array

Every time this line 

while (my $modelselect ne '10')

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executes, you are creating a brand new variable called $modelselect. It will always be uninitialised; and thus will never be eq to '10';

Try replacing that line with these two and you might have more success:

my $modelselect;
while ( $modelselect ne '10')

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