Re: newbie problem

[Simon Bracken <simon.bracken.@gecm.com>]

Graeme Wallace <Dizzy@interact.net.au> wrote:
>If I want to get user input for my program in the form of a  string of
>undefined length, how do I do so ?  If I set the string length to, say:
>
>help_me_please : String(1..20);
>
>I seem to be stuck with a string exactly that size.  What is the
>variable assignment which allows the actual length of the user input to
>determine the length of the string which the io system
>(ada.text_io.)gets ?
>
>G Wallace
>
>Thankyou.
>:-)
>

I'm a newbie too (with respect to the latest edition of Ada) here follows 
what I would suggest if you were using Ada83.  I expect that one of the 
new (Ada95) string types may be more convenient but this should do the 
trick (with necessary addition of "ada.")

The following is an abstract from a noddy application: it will allow the 
user to input a string of up to 80 characters.  The result is then 
manipulated in the normal way.  {it isn't perfect so if any other pedants 
are watching I know!}


with Text_IO;
procedure Example is

  subtype TEXT_STRING is STRING (1 .. 80);
  type VARYING is
    record
      Text : TEXT_STRING;
      Last : NATURAL;
    end record;

  Input_Record : VARYING;

.. blah

begin

    ...

    Text_IO.Get_Line (Input_Record.Text, Input_Record.Last);
    case Input_Record.Text (Input_Record.Text'First) is
      when 'P' =>
        if List = null then
          List := new PAGE_ITEM;
          List.Address := Input_Record.Text (2 .. 5);
          Current_Page_Ptr := List;
        else
     ...

end Example;

Hope this helps a bit.  I must aquaint myself with the new stuff.

Cheers,

Simon.