Re: Octal Conversion in VB

[Ludovic Brenta <ludovic.brenta@skynet.be>]

chrissy_brady1@yahoo.com (chrissy) writes:
> I was playing around in VB trying to come up with a simple application
                                                      ^^^^^^

See, comp.lang.ada?  This illustrates my earlier point about
disposable developers and disposable software.  Chrissy, this is not
against you, but why do you want a "simple" application?  Is it not
better to write a "correct" and "maintainable" application instead?

> to convert entered strings of alphanumerics into octal numbers.
> 
> This seemed to work, but the code looked ugly, and I'm not sure a
> truth table would support the conversion to infinity. Am I right?
> 
> Is there a better and tidier way?
> 
> 
> Hoping for some guidance

Here is a general algorithm that does what you want.  Note that you
need some mathematical background to understand why there are
log(N)/log(8) octal digits in any integer number.

HTH

-- 
Ludovic Brenta.


with Ada.Text_IO; use Ada.Text_IO;
with Ada.Integer_Text_IO; use Ada.Integer_Text_IO;
with Ada.Numerics.Elementary_Functions; use Ada.Numerics.Elementary_Functions;
procedure Decimal_To_Octal is
   function Read_Number return Integer is
      S : String (1 .. 100);
      Last : Natural;
      Result : Integer;
   begin
      Get_Line (S, Last);
      Get (From => S (1 .. Last), Item => Result, Last => Last);
      return Result;
   end Read_Number;

   Number_To_Convert : Integer := Read_Number;
begin
   Put (Item => Number_To_Convert); --  First print it as decimal
   Put (Item => Number_To_Convert, Base => 8); -- Print as octal.
   Put_Line;

   --  An alternative that doesn't use the Ada representation for octals:
   declare
      Number_Of_Digits : constant Integer :=
        1 + Integer (Log (Float (Number_To_Convert)) / Log (8.0));
      Octal_Digits : array (1 .. Number_Of_Digits) of Integer := (others => 0);
   begin
      for I in reverse Octal_Digits'Range loop
         Octal_Digits (I) := Number_To_Convert mod 8;
         Number_To_Convert := Number_To_Convert / 8;
      end loop;

      --  Now loop forward to print them
      for I in Octal_Digits'Range loop
         Put (Item => Octal_Digits (I), Width => 1);
      end loop;
   end;
exception
   when Data_Error =>
      Put_Line ("Please input a number in decimal.");
end Decimal_To_Octal;