Re: [boost] Stream input and output of NaN and infinity

From: Martin Bonner (martin.bonner_at_[hidden])
Date: 2006-05-15 15:47:17

-----Original Message-----
Robert Ramey wrote:
 
> Peter Dimov wrote:
>
>> It depends. Where do you draw the line? Is inf a number? Is -0.0 a
>> number? You have to have NaN if you want to be able to represent x/y
>> as a float.

> That's the problem.  x/y is not a valid operation if y is equal to 0. So
> it can't be represented as a number.

> The fact that C++ permits such an operation makes C++ different
> than arithmetic.  
"different than SOME arithmetics".  The arithmentic C++ (well, actually IEEE) defines is a perfectly sensible arithmetic.

> The fact that C++ uses operators like "/" and defines them
> similar to - but not identical to - the way they are defined by
> standard arithmetic 

Granted.  It isn't the standard arithmetic.

> is the source of all these problems.  
What problems?  (Apart from the extra work involved for authors of libraries like serialization I mean!)

> I say that C++ should be changed to so that the floats and operators which
> apply to them should implement what people expect from arithmetic operators.

Yes, but realistically that is never going to happen.

Wouldn't it be better to support the use-cases that people have in real code?

-- 
Martin Bonner
Pi Technology, Milton Hall, Ely Road,
Milton, Cambridge, CB4 6WZ
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