Difference between revisions of "cpp/numeric/ratio/ratio equal"
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| − | {{cpp/title | ratio_equal}} | + | {{cpp/title|ratio_equal}} |
{{cpp/numeric/ratio/navbar}} | {{cpp/numeric/ratio/navbar}} | ||
| − | {{ | + | {{ddcl|header=ratio|since=c++11|1= |
| − | + | ||
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template< class R1, class R2 > | template< class R1, class R2 > | ||
| − | struct ratio_equal : std::integral_constant; | + | struct ratio_equal : std::integral_constant<bool, /* see below */> { }; |
}} | }} | ||
| − | |||
| − | If the ratios R1 and R2 are equal, provides the member constant {{ | + | If the ratios {{tt|R1}} and {{tt|R2}} are equal, provides the member constant {{c|value}} equal {{c|true}}. Otherwise, {{c|value}} is {{c|false}}. |
| − | === Helper variable template === | + | ===Helper variable template=== |
| − | {{ddcl | since=c++17 | 1= | + | {{ddcl|since=c++17|1= |
template< class R1, class R2 > | template< class R1, class R2 > | ||
| − | + | constexpr bool ratio_equal_v = ratio_equal<R1, R2>::value; | |
}} | }} | ||
| − | {{cpp/types/integral_constant/inherit | {{c|1=R1::num == R2::num && R1::den == R2::den}} }} | + | {{cpp/types/integral_constant/inherit|{{c|1=R1::num == R2::num && R1::den == R2::den}}}} |
===Possible implementation=== | ===Possible implementation=== | ||
{{eq fun | {{eq fun | ||
| − | + | |1= | |
template< class R1, class R2 > | template< class R1, class R2 > | ||
struct ratio_equal : public std::integral_constant < | struct ratio_equal : public std::integral_constant < | ||
| Line 31: | Line 28: | ||
===Example=== | ===Example=== | ||
{{example | {{example | ||
| − | + | |code= | |
| − | + | ||
#include <iostream> | #include <iostream> | ||
#include <ratio> | #include <ratio> | ||
| − | + | ||
int main() | 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= | |
| − | 2/3 == | + | 2/3 == 6/9 |
}} | }} | ||
===See also=== | ===See also=== | ||
{{dsc begin}} | {{dsc begin}} | ||
| − | + | {{dsc inc|cpp/numeric/ratio/dsc ratio_not_equal}} | |
{{dsc end}} | {{dsc end}} | ||
| − | + | {{langlinks|de|es|fr|it|ja|pt|ru|zh}} | |
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Latest revision as of 14:46, 24 September 2024
| 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.
Contents |
[edit] 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> |
[edit] Possible implementation
template< class R1, class R2 > struct ratio_equal : public std::integral_constant < bool, R1::num == R2::num && R1::den == R2::den > {}; |
[edit] Example
Run this code
#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:
2/3 == 6/9
[edit] See also
| (C++11) |
compares two ratio objects for inequality at compile-time (class template) |
