Proper markup for source code in para?

Hello!

I am not sure how to markup the following things:

o Source code in <para> etc like:
   <para>This code <?>printf("abc") && do() || but()</?>

o lines of an config file like:

   <para>To enable TZU add

    <?>tzu1 = "tz:0:9"
       tzu2 = "tz:1:1"</?>

   to your file.</para>

I would  appreciate every hint.

Thanks,

Oliver