std::common_type(std::chrono::duration) (3) Linux Manual Page

std::common_type(std::chrono::duration) – std::common_type(std::chrono::duration)

Synopsis

template <class Rep1, class Period1, class Rep2, class Period2>

struct common_type<std::chrono::duration<Rep1, Period1>,

                   std::chrono::duration<Rep2, Period2>> {
    (since C++ 11)

        typedef std::chrono::duration<

            typename std::common_type<Rep1, Rep2>::type, /*see note*/> type;
};

Exposes the type named type, which is the common type of two std::chrono::durations.

Note

The period of the resulting duration is the greatest common divisor of Period1 and Period2.

Example

// Run this code

#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

common_type determines the common type of a group of types
            (class template)
(C++11)