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std:: ratio_less

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Compile-time rational arithmetic
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ratio_less
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Defined in header <ratio>
template < class R1, class R2 >
struct ratio_less : std:: integral_constant < bool , /* see below */ > { } ;
(since C++11)

If the ratio R1 is less than the ratio R2 , provides the member constant value equal true . Otherwise, value is false .

Contents

Helper variable template

template < class R1, class R2 >
constexpr bool ratio_less_v = ratio_less < R1, R2 > :: value ;
(since C++17)

Inherited from std:: integral_constant

Member constants

value
[static]
true if R1 :: num * R2 :: den < R2 :: num * R1 :: den , or equivalent expression that avoids overflow, 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 >

Example

Run this code 
#include <iostream>
#include <ratio>
int main()
{
    using x = std::ratio<69, 90>;
    using y = std::ratio<70, 90>;
    if constexpr (std::ratio_less_v<x, y>)
        std::cout << x::num << '/' << x::den << " < "
                  << y::num << '/' << y::den << '\n';
}

Output: 

23/30 < 7/9

See also

(C++11)
compares two ratio objects for greater than at compile-time
(class template)