std::chrono...time_point)(3)

🎀 NAME 🎀

This is the std::chrono::ceil(std::chrono::time_point) page from the C++ Standard Libary, and the NAME line is literally std::chrono::ceil(std::chrono::time_point) - std::chrono::ceil(std::chrono::time_point). Yes bestie, it says the same iconic thing twice — we love a consistent queen 💅.

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✨ Synopsis ✨

          Defined in header <chrono>
          template< class ToDuration, class Clock, class Duration >

          constexpr std::chrono::time_point<Clock, ToDuration>
       (since C++17)

              ceil( const std::chrono::time_point<Clock, Duration>& tp );

It returns the smallest time point t representable in ToDuration that is greater or equal to tp. That's the whole vibe: round that time point up, no cap.

Also important, and this is the function being a little gatekeeper: it does not participate in overload resolution unless ToDuration is a specialization of std::chrono::duration. Periodt.

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🫶 Parameters 🫶

• tp — time point to round up.

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💖 Return value 💖

tp rounded up to the next time point using duration of type ToDuration.

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🧚 Possible implementation 🧚

Here's how it could look under the hood, exactly as the page shows it:

          namespace detail
          {
              template<class> 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 Clock, class FromDuration,
                   class = std::enable_if_t<detail::is_duration_v<To>>>
          constexpr std::chrono::time_point<Clock, To>
              ceil(const std::chrono::time_point<Clock, FromDuration>& tp)
          {
              return std::chrono::time_point<Clock, To>{
                         std::chrono::ceil<To>(tp.time_since_epoch())};
          }

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🌸 Example 🌸

       // Run this code

        #include <chrono>
        #include <iostream>
        #include <string>

        template<typename TimePoint>
        std::string to_string(const TimePoint& time_point)
        {
            return std::to_string(time_point.time_since_epoch().count());
        }

        int main()
        {
            using namespace std::literals::chrono_literals;
            using Sec = std::chrono::seconds;

            std::cout << "Time point\t" "Cast\t" "Floor\t" "Round\t" "Ceil\n";
            std::cout << "(ms)\t\t"     "(s)\t"  "(s)\t"   "(s)\t"   "(s)\n";
            for (const auto value_ms : {5432ms, 5678ms})
            {
                std::chrono::time_point<std::chrono::system_clock,
       std::chrono::milliseconds>
                    time_point_ms(value_ms);

                std::cout
                    << to_string(time_point_ms) << "\t\t"
                    <<
       to_string(std::chrono::time_point_cast<Sec>(time_point_ms)) << '\t'
                    << to_string(std::chrono::floor<Sec>(time_point_ms)) <<
       '\t'
                    << to_string(std::chrono::round<Sec>(time_point_ms)) <<
       '\t'
                    << to_string(std::chrono::ceil<Sec>(time_point_ms)) <<
       '\n';
            }
        }

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⭐ Output ⭐

        Time point      Cast    Floor   Round   Ceil
        (ms)            (s)     (s)     (s)     (s)
        5432            5       5       5       6
        5678            5       5       6       6

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👑 See also 👑

• time_point_cast (C++11) — converts a time point to another time point on the same clock, with a different duration (function template).
• floor(std::chrono::time_point) (C++17) — converts a time_point to another, rounding down (function template).
• round(std::chrono::time_point) (C++17) — converts a time_point to another, rounding to nearest, ties to even (function template).
• ceil(std::chrono::duration) (C++17) — converts a duration to another, rounding up (function template).
• ceil, ceilf (C++11), ceill (C++11) — nearest integer not less than the given value (function).

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Okay that's the whole page, bestie 🫶💖 Source/version: http://cppreference.com. Date: 2024.06.10. Page: std::chrono...time_point)(3). Now go round those time points up and slay ✨💅