Check floats for .nan

[Sean Kelly]

BCS wrote:
> Reply to acarion,
> 
>> I have this code:
>>
>> float number=getFloat();
>> assert(number!=float.nan); //this passes
> 
> IIRC this will also pass:
> 
> assert(float.nan != float.nan);
> 
> this is because D used IEEE floating point semantics. Under IEEE a 
> comparison with NaN will always be  not equal
> 
> If you want to test for nan use "testedValue !<>= 0"* or the isnan function

I tend to use:

testedValue !<>= testedValue

Though I've occasionally wondered whether the 'is' identity operator 
should work for checking against nan:

testedValue is float.nan



Sean