Re: [boost] [serialization] Serialisation/deserialisation offloating-point values

From: Paul A Bristow (pbristow_at_[hidden])
Date: 2006-03-15 10:23:50

| -----Original Message-----
| From: boost-bounces_at_[hidden] 
| [mailto:boost-bounces_at_[hidden]] On Behalf Of Janek Kozicki
| Sent: 15 March 2006 12:56
| To: boost_at_[hidden]
| Subject: Re: [boost] [serialization] 
| Serialisation/deserialisation offloating-point values
| 
| Paul A Bristow said:     (by the date of Wed, 15 Mar 2006 
| 11:00:23 -0000)
| 
| > | The problem is clearly with the *de*serialisation.
| > | 
| > | Tracing back through the functions, this seems to be the 
| function (in 
| > | basic_text_iprimitive.hpp) that reads doubles from XML files:
| > | 
| > |     void load(T & t)
| > |     {
| > |         if(is.fail())
| > |             
| > | boost::throw_exception(archive_exception(archive_exception::st
| > | ream_error));
| > |         is >> t;
| > |     }
| > | 
| > | This suggests that it is a broken feature of Microsoft's 
| > | operator>> for doubles read from filestreams.
| 
| 
| why not just read the string, ans use boost::lexical_cast<double> ?
| 
| -- 
| Janek Kozicki                                                 

I fear that lexical_cast uses the same method of reading from a stringstream
:-((

And that our testing of lexical_cast is insufficient to catch it. 

Some very rough tests of lexical_cast suggest that several percent of not
very random double values fail to loopback ( 1 bit wrong), but I don't have
time to work on this at present.

IMO this seems a Microsoft problem/feature.

Paul

-- 
Paul A Bristow
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