From_string(Arg : String) return Big_Integer

From_string(Arg : String) return Big_Integer

[soren rundgren]

This piece of code compile with no warnings;
   S: constant Big_Integer := 4547337172376300111955330758342147474062293202868155909489;
   T: constant Big_Integer := 4547337172376300111955330758342147474062293202868155909393;

However the runtime message is
raised CONSTRAINT_ERROR : bad input for 'Value: "4547337172376300111955330758342147474062293202868155909489"
[2021-01-09 15:58:43] process exited with status 1, elapsed time: 00.21s

Any ideas why?

Re: From_string(Arg : String) return Big_Integer

[AdaMagica]

Since Ada 202X is not yet released, this package is not yet fully implemented. (I had a conversation with AdaCore about a similar case a year ago.)

Re: From_string(Arg : String) return Big_Integer

[soren rundgren]

lördag 9 januari 2021 kl. 18:00:36 UTC+1 skrev AdaMagica:
> Since Ada 202X is not yet released, this package is not yet fully implemented. (I had a conversation with AdaCore about a similar case a year ago.)

Re: From_string(Arg : String) return Big_Integer

[soren rundgren]

lördag 9 januari 2021 kl. 18:00:36 UTC+1 skrev AdaMagica:
> Since Ada 202X is not yet released, this package is not yet fully implemented. (I had a conversation with AdaCore about a similar case a year ago.)

I managed to make a very baic solution by creating my own:

   function My_From_String(S : String) return Big_Integer is
      sum : Big_Integer := 0;
      Len : constant Integer := S'Length;
      i : Integer := 1;
   begin
      -- Ada.Text_IO.Put_Line("My_From_String.S = " & S);
      while i <= Len loop
         case S(i) is -- i = Len : Len - Len = 0,
                      -- i = 1 : Len - 1
            when '1' => sum := sum + 1*10**(Len - i);
            when '2' => sum := sum + 2*10**(Len - i);
            when '3' => sum := sum + 3*10**(Len - i);
            when '4' => sum := sum + 4*10**(Len - i);
            when '5' => sum := sum + 5*10**(Len - i);
            when '6' => sum := sum + 6*10**(Len - i);
            when '7' => sum := sum + 7*10**(Len - i);
            when '8' => sum := sum + 8*10**(Len - i);
            when '9' => sum := sum + 9*10**(Len - i);
            when others => null;
         end case;
         i := i + 1;
      end loop;
      return sum;
   end My_From_String;

Re: From_string(Arg : String) return Big_Integer

[soren rundgren]

lördag 9 januari 2021 kl. 18:00:36 UTC+1 skrev AdaMagica:
> Since Ada 202X is not yet released, this package is not yet fully implemented. (I had a conversation with AdaCore about a similar case a year ago.)

I managed to make a very basic solution by creating my own:

   function My_From_String(S : String) return Big_Integer is
      sum : Big_Integer := 0;
      Len : constant Integer := S'Length;
      i : Integer := 1;
   begin
      -- Ada.Text_IO.Put_Line("My_From_String.S = " & S);
      while i <= Len loop
         case S(i) is -- i = Len : Len - Len = 0,
                      -- i = 1 : Len - 1
            when '1' => sum := sum + 1*10**(Len - i);
            when '2' => sum := sum + 2*10**(Len - i);
            when '3' => sum := sum + 3*10**(Len - i);
            when '4' => sum := sum + 4*10**(Len - i);
            when '5' => sum := sum + 5*10**(Len - i);
            when '6' => sum := sum + 6*10**(Len - i);
            when '7' => sum := sum + 7*10**(Len - i);
            when '8' => sum := sum + 8*10**(Len - i);
            when '9' => sum := sum + 9*10**(Len - i);
            when others => null;
         end case;
         i := i + 1;
      end loop;
      return sum;
   end My_From_String;

Re: From_string(Arg : String) return Big_Integer

[DrPi]

Le 09/01/2021 à 21:11, soren rundgren a écrit :
> lördag 9 januari 2021 kl. 18:00:36 UTC+1 skrev AdaMagica:
>> Since Ada 202X is not yet released, this package is not yet fully implemented. (I had a conversation with AdaCore about a similar case a year ago.)
> 
> I managed to make a very basic solution by creating my own:
> 
>     function My_From_String(S : String) return Big_Integer is
>        sum : Big_Integer := 0;
>        Len : constant Integer := S'Length;
>        i : Integer := 1;
>     begin
>        -- Ada.Text_IO.Put_Line("My_From_String.S = " & S);
>        while i <= Len loop
>           case S(i) is -- i = Len : Len - Len = 0,
>                        -- i = 1 : Len - 1
>              when '1' => sum := sum + 1*10**(Len - i);
>              when '2' => sum := sum + 2*10**(Len - i);
>              when '3' => sum := sum + 3*10**(Len - i);
>              when '4' => sum := sum + 4*10**(Len - i);
>              when '5' => sum := sum + 5*10**(Len - i);
>              when '6' => sum := sum + 6*10**(Len - i);
>              when '7' => sum := sum + 7*10**(Len - i);
>              when '8' => sum := sum + 8*10**(Len - i);
>              when '9' => sum := sum + 9*10**(Len - i);
>              when others => null;
>           end case;
>           i := i + 1;
>        end loop;
>        return sum;
>     end My_From_String;
> 
A much simpler function for Integer :

    function Int_From_String (Str : String) return Integer is
       Num : Integer := 0;
    begin
       for C of Str loop
          Num := (Num * 10) + Integer'Value((1 => C));
       end loop;

       return Num;
    end Int_From_String;

Notes :
- I don't have a 202x compiler, so I can't check if it works with big ints.
- It does not manage the sign (like the function you designed).

Re: From_string(Arg : String) return Big_Integer

[Jeffrey R. Carter]

On 1/9/21 11:13 PM, DrPi wrote:
> 
>     function Int_From_String (Str : String) return Integer is
>        Num : Integer := 0;
>     begin
>        for C of Str loop
>           Num := (Num * 10) + Integer'Value((1 => C));
>        end loop;
> 
>        return Num;
>     end Int_From_String;
> 
> Notes :
> - It does not manage the sign (like the function you designed).

There's a fairly complete Value function for unbounded integers in 
PragmARC.Unbounded_Numbers.Integers at

https://github.com/jrcarter/PragmARC

It handles negative values and based values.

-- 
Jeff Carter
"Help! Help! I'm being repressed!"
Monty Python & the Holy Grail
67

Re: From_string(Arg : String) return Big_Integer

[Dmitry A. Kazakov]

On 2021-01-09 23:13, DrPi wrote:
> Le 09/01/2021 à 21:11, soren rundgren a écrit :
>> lördag 9 januari 2021 kl. 18:00:36 UTC+1 skrev AdaMagica:
>>> Since Ada 202X is not yet released, this package is not yet fully 
>>> implemented. (I had a conversation with AdaCore about a similar case 
>>> a year ago.)
>>
>> I managed to make a very basic solution by creating my own:
>>
>>     function My_From_String(S : String) return Big_Integer is
>>        sum : Big_Integer := 0;
>>        Len : constant Integer := S'Length;
>>        i : Integer := 1;
>>     begin
>>        -- Ada.Text_IO.Put_Line("My_From_String.S = " & S);
>>        while i <= Len loop
>>           case S(i) is -- i = Len : Len - Len = 0,
>>                        -- i = 1 : Len - 1
>>              when '1' => sum := sum + 1*10**(Len - i);
>>              when '2' => sum := sum + 2*10**(Len - i);
>>              when '3' => sum := sum + 3*10**(Len - i);
>>              when '4' => sum := sum + 4*10**(Len - i);
>>              when '5' => sum := sum + 5*10**(Len - i);
>>              when '6' => sum := sum + 6*10**(Len - i);
>>              when '7' => sum := sum + 7*10**(Len - i);
>>              when '8' => sum := sum + 8*10**(Len - i);
>>              when '9' => sum := sum + 9*10**(Len - i);
>>              when others => null;
>>           end case;
>>           i := i + 1;
>>        end loop;
>>        return sum;
>>     end My_From_String;
>>
> A much simpler function for Integer :
> 
>     function Int_From_String (Str : String) return Integer is
>        Num : Integer := 0;
>     begin
>        for C of Str loop

for C in Str'Range loop

>           Num := (Num * 10) + Integer'Value((1 => C));

    Num := Num * 10 + Character'Pos (C) - Character'Pos'('0');

> Notes :
> - I don't have a 202x compiler, so I can't check if it works with big ints.
> - It does not manage the sign (like the function you designed).

- It does not handle overflow;
- It does not handle missing numbers in the input;
- It does not handle malformed input;
- It does not handle bases other than 10;
- It does not handle blank characters at the ends.

Functions mimicking S'Value (X) cover only half of cases. For the other 
half you need to get the number from a part of the string, so you have 
to recognize the end of the number and return the index or position 
where it ends or another token begins.

-- 
Regards,
Dmitry A. Kazakov
http://www.dmitry-kazakov.de

Re: From_string(Arg : String) return Big_Integer

[DrPi]

>> A much simpler function for Integer :
>>
>>     function Int_From_String (Str : String) return Integer is
>>        Num : Integer := 0;
>>     begin
>>        for C of Str loop
> 
> for C in Str'Range loop
In this case, C is a universal integer, not a character...

> 
>>           Num := (Num * 10) + Integer'Value((1 => C));
> 
>     Num := Num * 10 + Character'Pos (C) - Character'Pos'('0');
... so you have to use :
Num := Num * 10 + Character'Pos (Str(C)) - Character'Pos'('0');

I prefer this construct but when I quickly tried it, it did'nt work. 
Surely a typo somewhere.

So either :

       for C of Str loop
          Num := (Num * 10) + Character'Pos (C) - Character'Pos ('0');
       end loop;

or :

       for Idx in Str'Range loop
          Num := (Num * 10) + Character'Pos (Str(Idx)) - Character'Pos 
('0');
       end loop;




> 
>> Notes :
>> - I don't have a 202x compiler, so I can't check if it works with big 
>> ints.
>> - It does not manage the sign (like the function you designed).
> 
> - It does not handle overflow;
It handles overflow.

> - It does not handle missing numbers in the input;
> - It does not handle malformed input;
> - It does not handle bases other than 10;
> - It does not handle blank characters at the ends.
Sure. A very simple implementation usable in a known and controlled context.
> 
> Functions mimicking S'Value (X) cover only half of cases. For the other 
> half you need to get the number from a part of the string, so you have 
> to recognize the end of the number and return the index or position 
> where it ends or another token begins.
> 

Re: From_string(Arg : String) return Big_Integer

[Dmitry A. Kazakov]

On 2021-01-10 16:48, DrPi wrote:

> So either :
> 
>        for C of Str loop
>           Num := (Num * 10) + Character'Pos (C) - Character'Pos ('0');
>        end loop;
> 
> or :
> 
>        for Idx in Str'Range loop
>           Num := (Num * 10) + Character'Pos (Str(Idx)) - Character'Pos 
> ('0');
>        end loop;

Just for fun:

    subtype Digit is Character range '0'..'9';
    Encode : constant array (Digit) of Integer := (0,1,2,3,4,5,6,7,8,9);

    for ... loop
       Num := Num * 10 + Encode (C);

>> - It does not handle overflow;
> It handles overflow.

Only if Constraint_Error must be the result.

-- 
Regards,
Dmitry A. Kazakov
http://www.dmitry-kazakov.de

Re: From_string(Arg : String) return Big_Integer

[DrPi]

Le 10/01/2021 à 17:02, Dmitry A. Kazakov a écrit :
> On 2021-01-10 16:48, DrPi wrote:
> 
>> So either :
>>
>>        for C of Str loop
>>           Num := (Num * 10) + Character'Pos (C) - Character'Pos ('0');
>>        end loop;
>>
>> or :
>>
>>        for Idx in Str'Range loop
>>           Num := (Num * 10) + Character'Pos (Str(Idx)) - Character'Pos 
>> ('0');
>>        end loop;
> 
> Just for fun:
> 
>     subtype Digit is Character range '0'..'9';
>     Encode : constant array (Digit) of Integer := (0,1,2,3,4,5,6,7,8,9);
> 
>     for ... loop
>        Num := Num * 10 + Encode (C);
> 
Nice one !

>>> - It does not handle overflow;
>> It handles overflow.
> 
> Only if Constraint_Error must be the result.
> 
Right.