std::chrono::floor(std::chrono::duration) - cppreference.com (original) (raw)
| | | | | ------------------------------------------------------------------------------------------------------------------------------------------------------ | | ------------- | | template< class ToDuration, class Rep, class Period > constexpr ToDuration floor( const std::chrono::duration<Rep, Period>& d ); | | (since C++17) |
Returns the greatest duration t representable in ToDuration that is less or equal to d.
The function does not participate in the overload resolution unless ToDuration is a specialization of std::chrono::duration.
[edit] Parameters
[edit] Return value
d rounded down to a duration of type ToDuration.
[edit] Possible implementation
namespace detail { template inline constexpr bool is_duration_v = false; template<class Rep, class Period> inline constexpr bool is_duration_v< std::chrono::duration<Rep, Period>> = true; } template<class To, class Rep, class Period, class = std::enable_if_t<detail::is_duration_v>> constexpr To floor(const duration<Rep, Period>& d) { To t = std::chrono::duration_cast(d); if (t > d) return t - To{1}; return t; }
[edit] Example
#include #include #include int main() { using namespace std::chrono_literals; std::cout << "Duration\tFloor\tRound\tCeil\n"; for (using Sec = std::chrono::seconds; auto const d : {+4999ms, +5000ms, +5001ms, +5499ms, +5500ms, +5999ms, -4999ms, -5000ms, -5001ms, -5499ms, -5500ms, -5999ms}) std::cout << std::showpos << d << "\t\t" << std::chrono::floor(d) << '\t' << std::chrono::round(d) << '\t' << std::chrono::ceil (d) << '\n'; }
Output:
Duration Floor Round Ceil +4999ms +4s +5s +5s +5000ms +5s +5s +5s +5001ms +5s +5s +6s +5499ms +5s +5s +6s +5500ms +5s +6s +6s +5999ms +5s +6s +6s -4999ms -5s -5s -4s -5000ms -5s -5s -5s -5001ms -6s -5s -5s -5499ms -6s -5s -5s -5500ms -6s -6s -5s -5999ms -6s -6s -5s