std::time

 

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parse (C++20)
C-style date and time

 

C-style date and time utilities

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difftime

time

clock

timespec_get (C++17)

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asctime

ctime

strftime

wcsftime

gmtime

localtime

mktime

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CLOCKS_PER_SEC

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tm

time_t

clock_t

timespec (C++17)

 

Defined in header <ctime>
std::time_t time( std::time_t* arg );

Returns the current calendar time encoded as a std::time_t object, and also stores it in the object pointed to by arg, unless arg is a null pointer.

Parameters

arg

-

pointer to a std::time_t object to store the time, or a null pointer

Return value

Current calendar time encoded as std::time_t object on success, (std::time_t)(-1) on error. If arg is not null, the return value is also stored in the object pointed to by arg.

Notes

The encoding of calendar time in std::time_t is unspecified, but most systems conform to the POSIX specification and return a value of integral type holding 86400 times the number of calendar days since the Epoch plus the number of seconds that have passed since the last midnight UTC. Most notably, POSIX time does not (and can not) take leap seconds into account, so that this integral value is not equal to the number of S.I. seconds that have passed since the epoch, but rather is reduced with the number of leap seconds that have occurred since the epoch. Implementations in which std::time_t is a 32-bit signed integer (many historical implementations) fail in the year 2038.

Example

Run this code

#include <ctime>
#include <iostream>
 
int main()
{
    std::time_t result = std::time(nullptr);
    std::cout << std::asctime(std::localtime(&result))
              << result << " seconds since the Epoch\n";
}

Possible output:

Wed Sep 21 10:27:52 2011
1316615272 seconds since the Epoch

See also

timespec_get (C++17)	returns the calendar time in seconds and nanoseconds based on a given time base (function)
localtime	converts time since epoch to calendar time expressed as local time (function)
gmtime	converts time since epoch to calendar time expressed as Universal Coordinated Time (function)
system_clock (C++11)	wall clock time from the system-wide realtime clock (class)
C documentation for time