.NET's double.NaN - how does this counterintuitive feature work?
- by GeReV
I stumbled upon the definition of double.NaN in code:
public const double NaN = (double)0.0 / (double)0.0;
This is done similarly in PositiveInfinity and NegativeInfinity.
double.IsNaN (with removing a few #pragmas and comments) is defined as:
[Pure]
[ReliabilityContract(Consistency.WillNotCorruptState, Cer.Success)]
public static bool IsNaN(double d)
{
if (d != d)
{
return true;
}
else
{
return false;
}
}
This is, by far, the most counterintuitive thing I have ever seen in the .NET framework.
How is 0.0 / 0.0 represented "behind the scenes"? How can division by 0 be possible in double, and why does NaN != NaN?
