std::common_type(std::chrono::duration)
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) |
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公开名为type，这是两种常见的类型。std::chrono::durationS.
注
产生的持续时间的周期是Period1和Period2...
例
二次
#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";
}二次
产出：
二次
30ms - 1100us = 28900二次
另见
common_type (C++11) | determines the common type of a group of types (class template) |
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? cppreference.com在CreativeCommonsAttribution下授权-ShareAlike未移植许可v3.0。
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