GNAT for loop can't count!

GNAT for loop can't count!

[William Paul Berriss]

Hi

I use GNAT Ada95 compiler v3.07 on a Sun SPARC 5 runnig Solaris 2.5.

I have  very simple for loop that should count upwards from 118 to 129
but it counts 118, ..., 126, 127, -128, -127  (i.e. changes to
Negative after 127)

Here is the loop:

      for P in Pixel(Firstp)..Pixel(Lastp) loop             

        Ada.Integer_Text_IO.Put(Integer(P));
        Ada.Text_IO.New_line;

      end loop;

Where  Pixel is Integer range 0..255
and
Firstp and Lastp at this point are 118 and 129 respectively.
Both of type Pixel.

Very weird!

Any advice or helpful ideas most welcome indeed!!!!!!

Will Berriss
------------

-- 

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Re: GNAT for loop can't count!

[Matthew Heaney]

In article <33DCBE03.27E8@reading.ac.uk>, William Paul Berriss
<W.P.Berriss@reading.ac.uk> wrote:


>I use GNAT Ada95 compiler v3.07 on a Sun SPARC 5 runnig Solaris 2.5.

This is a very old version of GNAT; the current public release is 3.09. 
Have you considered upgrading?

Also, there is a discussion list for GNAT specificially, called
<mailto:chat@gnat.com>.  Go to the ACT website at <http://www.gnat.com> to
get info about signing up, and consider posting GNAT-specific queries
there.


>I have  very simple for loop that should count upwards from 118 to 129
>but it counts 118, ..., 126, 127, -128, -127  (i.e. changes to
>Negative after 127)
>
>Here is the loop:
>
>      for P in Pixel(Firstp)..Pixel(Lastp) loop             
>
>        Ada.Integer_Text_IO.Put(Integer(P));
>        Ada.Text_IO.New_line;
>
>      end loop;
>
>Where  Pixel is Integer range 0..255
>and
>Firstp and Lastp at this point are 118 and 129 respectively.
>Both of type Pixel.

What is type Pixal? Is it 

   subtype Pixal is Integer range 0 .. 255;

If so, then why did you declare your loop as you did?  Why the cast to
Pixal type, if Firstp and Lastp are already type Pixal?  Why not

   for P in Pixal range Firstp .. Lastp loop

Also, why did you cast the loop index to type integer, if Pixal is already
a subtype of Integer?  Why not

   Ada.Integer_Text_IO.Put (P);

It would help if you showed the _exact_ declaration of type Pixal.

--------------------------------------------------------------------
Matthew Heaney
Software Development Consultant
<mailto:matthew_heaney@acm.org>
(818) 985-1271

Re: GNAT for loop can't count!

[Robert Dewar]

William Berris says

<<I use GNAT Ada95 compiler v3.07 on a Sun SPARC 5 runnig Solaris 2.5.>>

This is quite a bit out of date by now, 3.09 was publicly released quite
a while ago, I suggest updating to this version. If you *do* think you
have discovered a bug, please follow the directions in the documentation
and submit a bug report.

Re: GNAT for loop can't count!

[Anonymous]

On Mon, 28 Jul 1997 16:42:59 +0100, William Paul Berriss
<W.P.Berriss@reading.ac.uk> wrote:

>       for P in Pixel(Firstp)..Pixel(Lastp) loop             
> 
>         Ada.Integer_Text_IO.Put(Integer(P));
>         Ada.Text_IO.New_line;
> 
>       end loop;
> 
> Where  Pixel is Integer range 0..255
> and
> Firstp and Lastp at this point are 118 and 129 respectively.
> Both of type Pixel.

GNAT 3.07/Solaris/Sparc:

with Ada.Text_Io;

use Ada;
procedure Junk is
   subtype Pixel is Integer range 0 .. 255;

   Firstp : Pixel;
   Lastp  : Pixel;
begin -- Junk
   Firstp := 118;
   Lastp  := 129;

   Text_Io.Put_Line (Pixel'Image (Firstp) & Pixel'Image (Lastp) );

   for P in Pixel (Firstp) .. Pixel (Lastp) loop
      Text_IO.Put_Line (Integer'Image (Integer (P) ) );
   end loop;

   Text_Io.Skip_Line;

   for P in Firstp .. Lastp loop
      Text_Io.Put_Line (Pixel'Image (P) );
   end loop;
end Junk;

Output:

 118 129
 118
 119
 120
 121
 122
 124
 125
 126
 127
 129

 118
 119
 120
 121
 122
 123
 124
 125
 126
 127
 128
 129


Jeff Carter  PGP:1024/440FBE21
My real e-mail address: ( carter @ innocon . com )
"Now go away or I shall taunt you a second time."
Monty Python & the Holy Grail

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