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std::ratio_equal - cppreference.com

From cppreference.com

template< class R1, class R2 > struct ratio_equal : std::integral_constant<bool, /* see below */> { };

 (since C++11)

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

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

Member functions

converts the object to bool, returns value
(public member function)
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()
{
    constexpr bool equ = std::ratio_equal_v<std::ratio<2,3>,
                                            std::ratio<6,9>>;
    static_assert(equ);
    std::cout << "2/3 " << (equ ? "==" : "!=") << " 6/9\n";
}

Output:

See also