std::ratio_add (3) - Linux Manuals

std::ratio_add: std::ratio_add

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()
  {
      typedef std::ratio<2, 3> two_third;
      typedef std::ratio<1, 6> one_sixth;

      typedef std::ratio_add<two_third, one_sixth> sum;
      std::cout << "2/3 + 1/6 = " << sum::num << '/' << sum::den << '\n';
  }

Output:

  2/3 + 1/6 = 5/6