std::chrono::time_point - cppreference.com (original) (raw)
| | | | | --------------------------------------------------------------------------------------- | | ------------- | | template< class Clock, class Duration = typename Clock::duration > class time_point; | | (since C++11) |
Class template std::chrono::time_point represents a point in time. It is implemented as if it stores a value of type Duration indicating the time interval from the start of the Clock's epoch.
| Clock must meet the requirements for Clock or be std::chrono::local_t(since C++20). | (until C++23) |
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Contents
[edit] Member types
| Type | Description |
|---|---|
| the clock on which this time point is measured (typedef) | |
| a std::chrono::duration type used to measure the time since epoch (typedef) | |
| an arithmetic type representing the number of ticks of the duration (typedef) | |
| a std::ratio type representing the tick period of the duration (typedef) |
[edit] Member functions
| (constructor) | constructs a new time point (public member function) [edit] |
|---|---|
| time_since_epoch | returns the time point as duration since the start of its clock (public member function) [edit] |
| operator+=operator-= | modifies the time point by the given duration (public member function) [edit] |
| operator++operator++(int)operator--operator--(int)(C++20) | increments or decrements the duration (public member function) [edit] |
| min[static] | returns the time point corresponding to the smallest duration (public static member function) [edit] |
| max[static] | returns the time point corresponding to the largest duration (public static member function) [edit] |
[edit] Non-member functions
| operator+operator-(C++11) | performs add and subtract operations involving a time point (function template) [edit] |
|---|---|
| operator==operator!=operator<operator<=operator>operator>=operator<=>(C++11)(C++11)(removed in C++20)(C++11)(C++11)(C++11)(C++11)(C++20) | compares two time points (function template) [edit] |
| time_point_cast(C++11) | converts a time point to another time point on the same clock, with a different duration (function template) [edit] |
| floor(std::chrono::time_point)(C++17) | converts a time_point to another, rounding down (function template) [edit] |
| ceil(std::chrono::time_point)(C++17) | converts a time_point to another, rounding up (function template) [edit] |
| round(std::chrono::time_point)(C++17) | converts a time_point to another, rounding to nearest, ties to even (function template) [edit] |
[edit] Helper classes
[edit] Example
#include #include #include #include #include void slow_motion() { static int a[]{1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12}; // Generate Γ(13) == 12! permutations: while (std::ranges::next_permutation(a).found) {} } int main() { using namespace std::literals; // enables literal suffixes, e.g. 24h, 1ms, 1s. const std::chrono::time_point<std::chrono::system_clock> now = std::chrono::system_clock::now(); const std::time_t t_c = std::chrono::system_clock::to_time_t(now - 24h); std::cout << "24 hours ago, the time was " << std::put_time(std::localtime(&t_c), "%F %T.\n") << std::flush; const std::chrono::time_point<std::chrono::steady_clock> start = std::chrono::steady_clock::now(); std::cout << "Different clocks are not comparable: \n" " System time: " << now.time_since_epoch() << "\n" " Steady time: " << start.time_since_epoch() << '\n'; slow_motion(); const auto end = std::chrono::steady_clock::now(); std::cout << "Slow calculations took " << std::chrono::duration_cast<std::chrono::microseconds>(end - start) << " ≈ " << (end - start) / 1ms << "ms ≈ " // almost equivalent form of the above, but << (end - start) / 1s << "s.\n"; // using milliseconds and seconds accordingly }
Possible output:
24 hours ago, the time was 2021-02-15 18:28:52. Different clocks are not comparable: System time: 1666497022681282572ns Steady time: 413668317434475ns Slow calculations took 2090448µs ≈ 2090ms ≈ 2s.