Re: New to Ada need help implementing Warshall's algorithm

[Stephen Leake <stephen_leake@stephe-leake.org>]

On Friday, September 23, 2016 at 10:07:53 AM UTC-5, James Brewer wrote:
> 
> It is three diffent sets of data. I think I may try to simplify the input data to a 0,1 2d array for each set, read the set in and then process each set writing it to an output file (the last two I will have to figure out).

Here's a working program that does the IO, to get you started. It reads from a file, writes to standard out.

Reading the entire input line from the file, then processing it, simplifies debugging.

with Ada.Command_Line;
with Ada.Text_IO; use Ada.Text_IO;
procedure Warshall
is
   procedure Put_Usage
   is
   begin
      Put_Line ("Usage: warshall <input file name>");
   end Put_Usage;

   File : File_Type;
begin
   Open (File, In_File, Ada.Command_Line.Argument (1));

   loop
      exit when End_Of_File (File);

      declare
         Line : constant String := Get_Line (File);
         --  Each line should have format 'A B' where, A, B => 1 | 0
         A : Boolean;
         B : Boolean;
      begin
         if Line (1) = '0' then
            A := False;
         else
            A := True;
         end if;

         if Line (3) = '0' then
            B := False;
         else
            B := True;
         end if;

         --  FIXME: implement warshall's algorithm

         Put_Line ("A, B: " & Boolean'Image (A) & " " & Boolean'Image (B));
      end;
   end loop;
end Warshall;

given an input file:

0 1
1 0

this produces:

A, B: FALSE TRUE
A, B: TRUE FALSE

I'm happy to hear about an instructor using Ada to teach algorithms!

-- Stephe