std::chrono::time_point<Clock,Duration>:: time_point

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std::chrono::time_point
(1)
time_point ( ) ;
(since C++11)
(constexpr since C++14)
(2)
explicit time_point ( const duration & d ) ;
(since C++11)
(constexpr since C++14)
(3)
template < class Duration2 >
time_point ( const time_point < Clock, Duration2 > & t ) ;
(since C++11)
(constexpr since C++14)

Constructs a new time_point from one of several optional data sources.

1) Default constructor, creates a time_point representing the Clock 's epoch (i.e., time_since_epoch() is zero).
2) Constructs a time_point at Clock 's epoch plus d .
3) Constructs a time_point by converting t to duration . This constructor only participates in overload resolution if Duration2 is implicitly convertible to duration .

Parameters

d - a duration to copy from
t - a time_point to convert from

Example

Run this code 
#include <chrono>
#include <iostream>
 
using Clock = std::chrono::steady_clock;
using TimePoint = std::chrono::time_point<Clock>;
 
void print_ms(const TimePoint& point) 
{
    using Ms = std::chrono::milliseconds;
    const Clock::duration since_epoch = point.time_since_epoch();
    std::cout << std::chrono::duration_cast<Ms>(since_epoch) << '\n';
}
 
int main() 
{
    const TimePoint default_value = TimePoint(); // (1)
    print_ms(default_value); // 0ms
 
    const Clock::duration duration_4_seconds = std::chrono::seconds(4);
    const TimePoint time_point_4_seconds(duration_4_seconds); // (2)
    // 4 seconds from start of epoch
    print_ms(time_point_4_seconds); // 4000ms
 
    const TimePoint time_point_now = Clock::now(); // (3)
    print_ms(time_point_now); // 212178842ms
}

Possible output: 

0ms
4000ms
212178842ms

See also

constructs new duration
(public member function of std::chrono::duration<Rep,Period> )
(C++11)
converts a duration to another, with a different tick interval
(function template)
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