std::common_type(std::chrono::duration)
Defined in header <chrono> |
||
|---|---|---|
template <class Rep1, class Period1, class Rep2, class Period2>
struct common_type<std::chrono::duration<Rep1, Period1>,
std::chrono::duration<Rep2, Period2>> {
typedef std::chrono::duration<
typename std::common_type<Rep1, Rep2>::type, /*see note*/> type;
}; |
(since C++11) |
Exposes the type named type, which is the common type of two std::chrono::durations, whose period is the greatest common divisor of Period1 and Period2.
Note
The period of the resulting duration can be computed by forming a ratio of the greatest common divisor of Period1::num and Period2::num and the least common multiple of Period1::den and Period2::den.
Example
#include <type_traits>
#include <iostream>
#include <chrono>
// std::chrono already finds the greatest common divisor,
// likely using std::common_type<>. We make the type
// deduction externally.
template <typename T,typename S>
constexpr auto durationDiff(const T& t, const S& s)
-> typename std::common_type<T,S>::type
{
typedef typename std::common_type<T,S>::type Common;
return Common(t) - Common(s);
}
int main()
{
using namespace std::literals;
constexpr auto ms = 30ms;
constexpr auto us = 1100us;
constexpr auto diff = durationDiff(ms, us);
std::cout << ms.count() << "ms - " << us.count() << "μs = " << diff.count()
<< (std::is_same<decltype(diff), decltype(ms)>() ? "ms" : "μs")
<< '\n';
}
Output:
30ms - 1100μs = 28900μs
See also
|
(C++11)
|
specializes the std::common_type trait (class template specialization) |
|
(C++11)
|
determines the common type of a group of types (class template) |
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https://en.cppreference.com/w/cpp/chrono/duration/common_type
