std::chrono::time_point

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Date and time library

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time_point (C++11)
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std::chrono::time_point

Member functions
time_point::time_point
time_point::time_since_epoch
time_point::operator+=time_point::operator-=
time_point::operator++time_point::operator-- (C++20)(C++20)
time_point::min
time_point::max
Non-member functions
operator+operator-
operator==operator!=operator<operator<=operator>operator>=operator<=> (until C++20)(C++20)
time_point_cast
floor (C++17)
ceil (C++17)
round (C++17)
Helper classes
common_type
hash<std::chrono::time_point> (C++26)

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Defined in header`<chrono>`
template< class Clock, class Duration=typename Clock::duration >class time_point;		(since C++11)

Class templatestd::chrono::time_point represents a point in time. It is implemented as if it stores a value of typeDuration indicating the time interval from the start of theClock's epoch.

Clock must meet the requirements forClockor bestd::chrono::local_t(since C++20).

(until C++23)

[edit]Member types

Type	Description
`Clockclock`	the clock on which this time point is measured (typedef)
`Durationduration`	astd::chrono::duration type used to measure the time since epoch (typedef)
`duration::reprep`	an arithmetic type representing the number of ticks of the duration (typedef)
`duration::periodperiod`	astd::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

std::common_type<std::chrono::time_point> (C++11)	specializes thestd::common_type trait (class template specialization)[edit]
std::hash<std::chrono::time_point> (C++26)	hash support for`std::chrono::time_point` (class template specialization)

[edit]Example

Run this code

#include <algorithm>#include <chrono>#include <ctime>#include <iomanip>#include <iostream> void slow_motion(){staticint 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(){usingnamespace 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(); conststd::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(); constauto 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: 413668317434475nsSlow calculations took 2090448µs ≈ 2090ms ≈ 2s.