I want to encode solar mass as a std::ratio (in order to convert it to kg). How can I do such a thing if solar mass is 1.988478e+30 kg?
std::ratio<(unsigned long long)1'988'478e+30, 1> kg_to_solar_mass // overflow
Asked
Active
Viewed 163 times
0
hououin kyouma
- 47
- 6
-
Why not just use `double`? You only know the solar mass up to 7 significant digits anyway. – Thomas Apr 15 '20 at 17:35
-
ratio uses intmax_t as its templates – hououin kyouma Apr 15 '20 at 17:53
-
My point is, you don't need `std::ratio` if you just use `double`. – Thomas Apr 15 '20 at 18:31
-
Thanks, but simple `double` is not strong typed. What I want is actually `std::ratio` for `double`s, – hououin kyouma Apr 16 '20 at 07:21
1 Answers
0
A 64 bit unsigned integer (what the typical machine uses for a unsigned long long) has a max value of 18446744073709551615 (1.8446744073709551615e+19). That is orders of magnitude smaller then a 1'988'478e+39 (or even 1.989e+30) and is going to overflow the integer.
You're either going to have to switch to a different type that uses doubles or some "Big Int" library, or not specify a ratio for a single kilogram to a solar mass.
NathanOliver
- 171,901
- 28
- 288
- 402