The std::ratio_equal
class template provides a mechanism for comparing two std::ratio values for equality at compile
time, using rational arithmetic.
template <class R1, class R2> class ratio_equal: public see below {};
R1 and R2
must be instantiations of the std::ratio class template.
The value of std::ratio_equal<R1,R2>
is (R1::num==R2::num) && (R1::den==R2::den).
If the TR1 std::tr1::integral_constant class template is available,
then std::ratio_equal<R1,R2> derives from std::tr1::integral_constant<bool, value >. Otherwise, std::ratio_equal<R1,R2>
derives from an internal type that provides a static constant data member
value of type bool equal to value.
std::ratio_equal< std::ratio<1,3>, std::ratio<2,6> >::value == true std::ratio_equal< std::ratio<1,3>, std::ratio<1,6> >::value == false std::ratio_equal< std::ratio<1,3>, std::ratio<2,3> >::value == false std::ratio_equal< std::ratio<1,3>, std::ratio<1,3> >::value == true
Header
#include <ratio>