If you just want to avoid the warnings, you can always inhibit them with no warnings. See perllexwarn.

use warnings; 
..
# in the block
no warnings qw(uninitialized);
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Are you aware that skipblanks() does not iterate over @data? The following code should do the same as your function:

sub skipblanks {
#    my @data = @_;
    # you probably want $x = shift || 0;
    my $x    = shift;
#    foreach $x (@data) {
        if ($x) {
            $x =~ s/,/\./g;
        }
        return $x;
#   }
}
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