Defined in header <ratio>
template< class R1, class R2 >
using ratio_divide = /* see below */;

The alias template std::ratio_divide denotes the result of dividing 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 and Denom == R1::den * R2::num (computed without arithmetic overflow), U is std::ratio<Num, Denom>::num and V is std::ratio<Num, Denom>::den.


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_divide<R1, R2> be already reduced to lowest terms; for example, std::ratio_divide<std::ratio<1, 12>, std::ratio<1, 6>> is the same type as std::ratio<1, 2>.


#include <iostream>
#include <ratio>
int main()
    typedef std::ratio<2, 3> two_third;
    typedef std::ratio<1, 6> one_sixth;
    typedef std::ratio_divide<two_third, one_sixth> r;
    std::cout << "2/3 / 1/6 = " << r::num << '/' << r::den << '\n';


2/3 / 1/6 = 4/1

© cppreference.com
Licensed under the Creative Commons Attribution-ShareAlike Unported License v3.0.