Re: [Boost-users] [Boost-Users][serialization] Floating point precision

From: Robert Ramey (ramey_at_[hidden])
Date: 2007-02-28 16:35:15

You should have the ostream reference around somewhere.  In which case
you could just os.setprecision(..) somewhere.  If you did it before 
attaching
to the archive it would be global.  If you did it within a "save" it would
be local - but in theory not portable - in practice it might be just fine
for you.

Robert Ramey

jsanga_at_[hidden] wrote:
> Is there a way to specify the precision of doubles when writing to
> xml_oarchive? Refer to the output snippet below.
>
>        <Control class_id="3" tracking_level="0" version="1">
>                <Type>0</Type>
>                <LowMZ>5.0499999999999998</LowMZ>
>                <HiMZ>5.0999999999999996</HiMZ>
>
>
> I would like 5.05 and 5.1 for Low and High. Stepping through the code
> with the debugger I ended up in basic_text_oprimitive::save( const
> double t).
>
>   void save(const double t)
>    {
>        if(os.fail())
>
>
>
>
> boost::throw_exception(archive_exception(archive_exception::stream_error));
> os << std::setprecision(std::numeric_limits<double>::digits10 + 2);
> os << t; }
>
> where it seems the precision is fixed. The only solution I can seem
> to think of is to split the serialization, and on the output convert
> my double to string (with the correct precsion) and then serialize
> the string. Is there a different or better way?