Re: [boost] Spurious warning in lexical_cast.hpp

From: Paul A Bristow (pbristow_at_[hidden])
Date: 2006-08-02 15:35:19

|  -----Original Message-----
|  From: boost-bounces_at_[hidden] 
|  [mailto:boost-bounces_at_[hidden]] On Behalf Of Gennaro Prota
|  Sent: 02 August 2006 19:34
|  To: boost_at_[hidden]
|  Subject: Re: [boost] Spurious warning in lexical_cast.hpp
|  
|  On Wed, 2 Aug 2006 14:11:20 +0100, "Paul A Bristow"
|  <pbristow_at_[hidden]> wrote:
|  
|  >But this is STILL the WRONG formula for the number of digits!
|  >
|  >It should be max_digits10.
|  >
|  >stream.precision(2 + std::numeric_limits<Source>::digits * 
|  301/1000); 
|  >
|  >PLEASE can we get at long last get this right so that floats can be
|  >serialized without losing a few bits.
|  
|  I presume lexical_cast will be totally rewritten not too far in the
|  future, to optimize some specific conversions, as also recently
|  discussed. That's why I've tended to postpone issues about it. But if
|  you really feel strongly about this specific problem (please, say "I
|  do so swear" ;-)) I'll give it a thought.
|  
|  But...: are you serializing floating point values by means of
|  lexical_cast?

No - I meant 'stringizing' - but the same wrong formula has been used for
serialization.

Fortunately it just happens to give the right result for double - and most
people are using that.

But as a QOI issue, I think it looks bad, and may bite some poor
unsuspecting user.

Paul

---
Paul A Bristow
Prizet Farmhouse, Kendal, Cumbria UK LA8 8AB
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pbristow_at_[hidden]