Beginner's questions

[marcoschmidt@geocities.com (Marco Schmidt)]

I have to write my first longer program in Ada and could resolve all
questions except for those two using the reference manual. Maybe
someone could help me here... I'm using GNAT 3.11p for NT.

1) I couldn't find out how to use bitwise operations "and" and "or"
(which would be "and" / "or" in Pascal and "&" / "|" in C). Do I have
to include a certain package?

2) I want to use a fixed-size array of constant strings to store some
names which do not all have the same length, but no name is longer
than 20 characters. My approach looks like this:

  type t_my_array is array(0..17) of String;

  names : constant t_my_array := ("string 1", "string 2", ...,
    "string 18");

The compiler doesn't like this (unconstrained element type). If I
replace String with String(0..19), it is compiled, but a runtime error
is raised. How should I do it?

Thanks in advance,
Marco