my ($untainted) = ($_num =~  /^(.*)$/);
if ($untainted >= 0 and $untainted < 1) {
    $num = $untainted + 0.0;
}

##</code><code>##

for my $_num (0, 1, ".5", -0.5, 0.5, 9.00000999999, 0.0000099999999,
 "asdfads", "0.9999999999999999999999999999") {
    my $num;
    my ($untainted) = ($_num =~  /^(.*)$/);
    if ($untainted >= 0 and $untainted < 1) {
        $num = $untainted + 0.0;
    }
    print "$_num $untainted  $num\n";
}