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