David Abrahams wrote:
"Robert Ramey" <ramey@rrsd.com> writes:
I think we should go in the opposite direction. A float is a a legitmate floating point value. A union of float and some other special non-floating point values is something else.
Notwithstanding the fact that NaN is "not a number," it is a legitimate floating-point value, i.e. a legitimate value for the type float.
I guess it depends what one means by "legitimate". It is is certainly "legal" in C++ - no question about that fact. Its certainly not a number - no question about that either. The problem is that C++ makes float a union of two different things and that is what creates all the problems we have with it. C++ should correct this by making the result of arithmetic operations which result in Nan's either undefined or throw exceptions. Oh I know that this would break a lot of existing code. I would argue that such code is already broken anyway - it just looks like its working. Robert Ramey