What is the C++11 equivalent to boost::date_time::not_a_date_time?

Question

I\'m modifying an old project, and at the same time I\'m updating several things to bring it up to C++11.

I\'d like to replace various uses of boost::date_time with

Answer 1

Given the fact that it exists as part of a group

bool is_infinity() const
bool is_neg_infinity() const
bool is_pos_infinity() const
bool is_not_a_date_time() const

it is pretty clear that this is done by using a floating-point type for the internal representation and setting the value to a NaN (not-a-number).

In std::chrono, the representation type is required to be an arithmetic type. Floating-point types therefore qualify, and you can use the same trick.

Given a std::duration, you could then test it using

std::isnan(dur.count())

(Naturally, you should use a quiet NaN value, not a signalling NaN, so you don't trigger floating-point traps)