std::ratio_equal

< cpp‎ | numeric‎ | ratio

Defined in header `<ratio>`
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 > inline 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()
{
    constexpr bool equ = std::ratio_equal_v<std::ratio<2,3>,
                                            std::ratio<4,6>>;
    static_assert(equ == true);
    std::cout << "2/3 " << (equ ? "==" : "!=") << " 4/6\n";
}

Output:

2/3 == 4/6