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From: "Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de>
Subject: Re: Converting Integer / Float to String
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Date: Thu, 17 Jul 2008 11:24:51 +0200
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Date: 2008-07-17T11:24:51+02:00
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On Thu, 17 Jul 2008 10:32:59 +0200, Alexander Camek wrote:

> First of all, this was only a base to start discussion on it and at that 
> point I need some value to initial my float or integer value to get a proper 
> value if the string is malformed.

I don't think it is a good idea. Malformed document should be reported,
instead of being silently parsed.

> As far as I can tell, the background of the code snipplet is that the string 
> is given from an xml file which is parsed by glib xml and there I get all as 
> a string.

I see. Doesn't Glib's XML parser have a support for numeric parsing? I
mean, if you already use a parser then it is better to use it at full,
instead of adding other code.

> To your second question. The whitespaces are trimmed and I can only rely on 
> the point that there is a correct value in it,

But it can be like this:

<rubbish> 1.0 2 4 </rubbish>

Then what about encoded Unicode characters? Like "&#x1234". Does the parser
translate them? If it does, how does it this for non-Latin-1 characters? I
don't know it, but the parser could produce UTF-8 octets stored in Ada
String, which then would be OK to parse as if it were Latin-1... (:-))

> if not then the default value 
> will be set or at the beginning for initilisation 0.0 is used.

Well, the cases "there is no any number" and "the file contains rubbish"
are different to me. I would not use the default in the second case.

I have a library for parsing:

   http://www.dmitry-kazakov.de/ada/strings_edit.htm

Your sample code could look like:

begin
   Value := Strings_Edit.Floats.Value (Float_String);
exception
   when End_Error => -- No number
      Value := Default;
   when Data_Error => -- Wrong number, XML file is corrupt
       ...
   when Constraint_Error => -- Out of range
      ...
end;

If saturation of the input is OK, then

   Value (Float_String, ToFirst => True, ToLast => True);

that would saturate the input to the nearest bound instead of
Constraint_Error propagation.

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