"Robert Ramey" <ramey@rrsd.com> writes:
Its even worse, there is way to write portable code which will generate any specific one of the "undefined" types.
numeric_limits<float>::quiet_NaN()
Is "reasonably portable."
hmm - what's "reasonable portable" is hard to get a concensus on.
Let's put it this way: if numeric_limits<float>::has_quiet_NaN is true, numeric_limits<float>::quiet_NaN() is a portable way to get a non-signaling NaN of type float. If numeric_limits<float>::has_quiet_NaN is false, there's no representation of float with a non-signaling NaN value on the implementation. This is exactly as portable as an int with value 100,000: if numeric_limits<int>::max() >= 100000, int(100000) is a portable way to get an int with value 10000 non-signaling NaN. If numeric_limits<int>::max < 10000, there's no representation of int with value 100000 on the implementation. I hope you'll agree that an int with value 100000 is not too exotic, and that a program that expects to be able to handle such an int ain't "broke." -- Dave Abrahams Boost Consulting www.boost-consulting.com