my %formats = ( 1 => ' %s  ',
                2 => ' %s ', 
                3 => ' %s', 
                4 => '%s', 
              );

for my $x ("a", "bb", "ccc", "dddd") {
    printf $formats{length($x)}, $x; 
    print "\n";
}

######################
 a  
 bb 
 ccc
dddd