Re: From_string(Arg : String) return Big_Integer

[DrPi <314@drpi.fr>]

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.