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std::chrono::time_point

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< cpp‎ | chrono
 
 
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time_point
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Defined in header <chrono>
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)

Contents

[edit] Member types

Member type Definition
clock Clock, the clock on which this time point is measured
duration Duration, a std::chrono::duration type used to measure the time since epoch
rep Rep, an arithmetic type representing the number of ticks of the duration
period Period, a std::ratio type representing the tick period of the duration

[edit] Member functions

constructs a new time point
(public member function) [edit]
returns the time point as duration since the start of its clock
(public member function) [edit]
modifies the time point by the given duration
(public member function) [edit]
increments or decrements the duration
(public member function) [edit]
[static]
returns the time point corresponding to the smallest duration
(public static member function) [edit]
[static]
returns the time point corresponding to the largest duration
(public static member function) [edit]

[edit] Non-member functions

performs add and subtract operations involving a time point
(function template) [edit]
(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]
converts a time point to another time point on the same clock, with a different duration
(function template) [edit]
converts a time_point to another, rounding down
(function template) [edit]
converts a time_point to another, rounding up
(function template) [edit]
converts a time_point to another, rounding to nearest, ties to even
(function template) [edit]

[edit] Helper classes

specializes the std::common_type trait
(class template specialization) [edit]

[edit] Example

#include <algorithm>
#include <iostream>
#include <iomanip>
#include <ctime>
#include <chrono>
 
void slow_motion()
{
    static int a[] {1,2,3,4,5,6,7,8,9,10,11,12};
    while (std::ranges::next_permutation(a).found)
    { } // generates 12! permutations
}
 
int main()
{
    using namespace std::literals; // enables the usage of 24h, 1ms, 1s instead of
                                   // e.g. std::chrono::hours(24), accordingly
    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).count() << "µs ≈ "
      << (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.

[edit] See also

(C++11)
a time interval
(class template) [edit]