my $von = date('2011-05-02');
my $bis = date('2011-07-30');
my $rel_monate = int(($bis - $von)->month);
$von += $rel_monate.'M';
my $rel_tage_uebrig = ($bis - $von)->day;
print $rel_monate * 30 + $rel_tage_uebrig;