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::duration
s.
Note
The period of the resulting duration is the greatest common divisor of Period1
and Period2
.
std::common_type<>
is specialized for std::chrono::duration
.
Example
#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> 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() { typedef std::chrono::milliseconds milliseconds; typedef std::chrono::microseconds microseconds; auto ms = milliseconds(30); auto us = microseconds(1100); std::cout << ms.count() << "ms - " << us.count() << "us = " << durationDiff(ms,us).count() << "\n"; }
Output:
30ms - 1100us = 28900
See also
(C++11) | deduces the result type of a mixed-mode arithmetic expression (class template) |
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