std::ratio_equal

Defined in header <ratio>

template< class R1, class R2 >
struct ratio_equal : std::integral_constant;

If the ratios R1 and R2 are equal, provides the member constant value equal true. Otherwise, value is false.

Helper variable template

template< class R1, class R2 >
constexpr bool ratio_equal_v = ratio_equal<R1, R2>::value;

(since C++17)

Inherited from std::integral_constant

Member constants

value

[static]

true if R1::num == R2::num && R1::den == R2::den , false otherwise
(public static member constant)

Member functions

operator bool	converts the object to `bool`, returns `value` (public member function)
operator() (C++14)	returns `value` (public member function)

Member types

Type	Definition
`value_type`	`bool`
`type`	`std::integral_constant<bool, value>`

Possible implementation

template< class R1, class R2 >
struct ratio_equal : public std::integral_constant <
                                 bool,
                                 R1::num == R2::num && R1::den == R2::den
                            > {};

Example

#include <iostream>
#include <ratio>
  
int main()
{
    if(std::ratio_equal<std::ratio<2,3>, std::ratio<4,6>>::value) {
        std::cout << "2/3 == 4/6\n";
    } else {
        std::cout << "2/3 != 4/6\n";
    }
}

Output:

1	`2/3 == 4/6`