std::ratio_add - cppreference.com (original) (raw)
| | | | | ---------------------------------------------------------------------- | | ------------- | | template< class R1, class R2 > using ratio_add = /* see below */; | | (since C++11) |
The alias template std::ratio_add denotes the result of adding two exact rational fractions represented by the std::ratio specializations R1 and R2.
The result is a std::ratio specialization std::ratio<U, V>, such that given Num == R1::num * R2::den + R2::num * R1::den and Denom == R1::den * R2::den (computed without arithmetic overflow), U is std::ratio<Num, Denom>::num and V is std::ratio<Num, Denom>::den.
[edit] Notes
If U or V is not representable in std::intmax_t, the program is ill-formed. If Num or Denom is not representable in std::intmax_t, the program is ill-formed unless the implementation yields correct values for U and V.
The above definition requires that the result of std::ratio_add<R1, R2> be already reduced to lowest terms; for example, std::ratio_add<std::ratio<1, 3>, std::ratio<1, 6>> is the same type as std::ratio<1, 2>.
[edit] Example
#include #include int main() { using two_third = std::ratio<2, 3>; using one_sixth = std::ratio<1, 6>; using sum = std::ratio_add<two_third, one_sixth>; std::cout << "2/3 + 1/6 = " << sum::num << '/' << sum::den << '\n'; }
Output: