std::ratio_equal

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< cpp‎ | numeric‎ | ratio
 
 
Metaprogramming library
Type traits
Type categories
(C++11)
(C++14)  
(C++11)
(C++11)
(C++11)
(C++11)
(C++11)
(C++11)
(C++11)
Type properties
(C++11)
(C++11)
(C++14)
(C++11)
(C++11)(until C++20*)
(C++11)(deprecated in C++20)
(C++11)
Type trait constants
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(C++17)
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(C++11)(until C++20*)(C++17)
Compile-time rational arithmetic
Compile-time integer sequences
 
Compile time rational arithmetic
(C++11)
Arithmetic
(C++11)
Comparison
ratio_equal
(C++11)
(C++11)
 
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

See also

compares two ratio objects for inequality at compile-time
(class template)