std::ratio_add(3)

NAME
std::ratio_add - std::ratio_add

Synopsis
   Defined in header <ratio>
   template< class R1, class R2 > (since C++11)
   using ratio_add = /* see below */;
   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.

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>.

Example
// Run this code
 #include <iostream>
 #include <ratio>
 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:
 2/3 + 1/6 = 5/6