boostorg/spirit

Small bug in karma real_generator output.

IlyaKiparenko opened this issue · 1 comments

IlyaKiparenko commented

If I try to output number 0.099999999999999770 (double) with 16 digits precision, boost karma generates wrong output of "0.9999999999999999" which is 10 times larger. As far as I can tell this is an issue of log10 rounding, which for this number produces 15.0 exactly instead of 14.999.... in real_policies.hpp : fraction_part. This causes karma to not output a leading zero.

I'm not exactly sure, but I think this issue can be resolved by replacing floor(log10(n)) + 1 with ceil(log10(n)). Also there is probably other places in real generator where such issues can arise.

Kojoley commented

Looks exactly like #529

I'm not exactly sure, but I think this issue can be resolved by replacing floor(log10(n)) + 1 with ceil(log10(n)).

That won't work with powers of ten. ceil(log10(n + 1))) will.

Also there is probably other places in real generator where such issues can arise.

Or they are already workarounded in #629.