Re: [boost] [serialization] facets for non-finite numbers

From: Johan Råde (rade_at_[hidden])
Date: 2006-07-25 12:54:20

Johan Råde wrote:
> At the suggestion of Robert Ramey's, I have put together facets for 
> reading and writing non-finite numbers, such as infinity and 
> not-a-number, to text streams, in a consistent and portable way.
> 
> The code, with documentation and tests, is available in the Boost Vault,
> serialization/non_finite_num_facets.zip.
> 
> If there is enough interest in the code, I will submit it for a 
> mini-review, in order to have it added to the serialization lib.
> 
> ---------------------------------------------
> 
> What does the code do?
> 
> The following test fails on VC++ 7.1:
> 
>      stringstream s;
>      double x = numeric_limits<double>::infinity();
>      double y;
>      ss << x;
>      ss >> y;
>      assert(x == y);
> 
> The situation gets even worse when text files are required to
> be portable between different platforms.
> 
> But the following test succeeds:
> 
>      stringstream s;
> 
>      locale old_locale;
>      locale tmp_locale(old_locale, new extended_num_put<char>);
>      locale new_locale(tmp_locale, new extended_num_get<char>);
>      s.imbue(new_locale);
> 
>      double x = numeric_limits<double>::infinity();
>      double y;
>      ss << x;
>      ss >> y;
>      assert(x == y);
> 
> For more info, read the documentation.
> 
> ------------------------------------------------------------
> 
> --Johan Råde
> 
> _______________________________________________
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> 

I have uploaded a revised version with a more robust is_nan function.
The code is in the vault: serialization/non_finite_num_facets.zip.

--Johan Råde