for $format (qw{ %.6g  %6.6g %6g %.6f %6.6f %6f}){
        print "\n$format\n";
        for (12344.99, 1.12345678, 0.000000123, 0.12345678, 123.45678, 123456, 12345.678901){
                $str = sprintf "$format",$_;
                print length($str)." - '$str'\n";
        }
}

##</code><code>##


%.6g
5 - '12345'
7 - '1.12346'
8 - '1.23e-07'
8 - '0.123457'
7 - '123.457'
6 - '123456'
7 - '12345.7'

%6.6g
6 - ' 12345'
7 - '1.12346'
8 - '1.23e-07'
8 - '0.123457'
7 - '123.457'
6 - '123456'
7 - '12345.7'

%6g
6 - ' 12345'
7 - '1.12346'
8 - '1.23e-07'
8 - '0.123457'
7 - '123.457'
6 - '123456'
7 - '12345.7'

%.6f
12 - '12344.990000'
8 - '1.123457'
8 - '0.000000'
8 - '0.123457'
10 - '123.456780'
13 - '123456.000000'
12 - '12345.678901'

%6.6f
12 - '12344.990000'
8 - '1.123457'
8 - '0.000000'
8 - '0.123457'
10 - '123.456780'
13 - '123456.000000'
12 - '12345.678901'

%6f
12 - '12344.990000'
8 - '1.123457'
8 - '0.000000'
8 - '0.123457'
10 - '123.456780'
13 - '123456.000000'
12 - '12345.678901'