std::chrono::system_clock::from_time_t - cppreference.com (original) (raw)

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Date and time library

Time point time_point(C++11) clock_time_conversion(C++20) clock_cast(C++20) Duration duration(C++11) Clocks system_clock(C++11) steady_clock(C++11) is_clock(C++20) utc_clock(C++20) tai_clock(C++20) high_resolution_clock(C++11) gps_clock(C++20) file_clock(C++20) local_t(C++20) Time of day is_amis_pm(C++20)(C++20) make12make24(C++20)(C++20) hh_mm_ss(C++20) Calendar day(C++20) month(C++20) year(C++20) weekday(C++20) operator/(C++20) year_month_day(C++20) year_month_day_last(C++20) year_month_weekday(C++20) year_month_weekday_last(C++20) weekday_indexed(C++20) weekday_last(C++20) month_day(C++20) month_day_last(C++20) month_weekday(C++20) month_weekday_last(C++20) year_month(C++20) last_speclast(C++20)(C++20) chrono I/O parse(C++20) Time zone tzdb(C++20) tzdb_list(C++20) get_tzdbget_tzdb_listreload_tzdbremote_version(C++20)(C++20)(C++20)(C++20) sys_info(C++20) local_info(C++20) nonexistent_local_time(C++20) ambiguous_local_time(C++20) locate_zone(C++20) current_zone(C++20) time_zone(C++20) choose(C++20) zoned_traits(C++20) zoned_time(C++20) time_zone_link(C++20) leap_second(C++20) leap_second_info(C++20) get_leap_second_info(C++20) C-style date and time

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std::chrono::system_clock

Member functions
system_clock::now
system_clock::to_time_t
system_clock::from_time_t
Time point I/O
operator<<
formatterstd::chrono::sys\_time
from_stream

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| static std::chrono::system_clock::time_point from_time_t( std::time_t t ) noexcept; | | (since C++11) | | -------------------------------------------------------------------------------------------------------------- | | ------------- |

Converts t to a time point type, using the coarser precision of the two types.

If time_point has lower precision, it is implementation defined whether the value is rounded or truncated.

Contents

[edit] Parameters

t - std::time_t value to convert

[edit] Return value

A value of type std::chrono::system_clock::time_point representing t.

[edit] Example

Run this code

#include #include #include #include   int main() { using namespace std::chrono_literals;   const std::time_t t = std::time(nullptr); // usually has "1 second" precision   const auto from = std::chrono::system_clock::from_time_t(t);   std::this_thread::sleep_for(500ms);   const auto diff = std::chrono::system_clock::now() - from;   std::cout << diff << " (" << std::chrono::round<std::chrono::milliseconds>(diff) << ")\n"; }

Possible output:

987654321ns (987ms)

[edit] See also

to_time_t[static] converts a system clock time point to std::time_t (public static member function) [edit]

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