Defined in header <time.h>
int timespec_get( struct timespec *ts, int base );
(1) (since C11)
#define TIME_UTC /* implementation-defined */
(2) (since C11)
1) Modifies the timespec object pointed to by ts to hold the current calendar time in the time base base.
2) Expands to a value suitable for use as the base argument of timespec_get

Other macro constants beginning with TIME_ may be provided by the implementation to indicate additional time bases.

If base is TIME_UTC, then.

  • ts->tv_sec is set to the number of seconds since an implementation defined epoch, truncated to a whole value
  • ts->tv_nsec member is set to the integral number of nanoseconds, rounded to the resolution of the system clock


ts - pointer to an object of type struct timespec
base - TIME_UTC or another nonzero integer value indicating the time base

Return value

The value of base if successful, zero otherwise.


The POSIX function clock_gettime(CLOCK_REALTIME, ts) may also be used to populate a timespec with the time since the Epoch.


#include <stdio.h>
#include <time.h>
int main(void)
    struct timespec ts;
    timespec_get(&ts, TIME_UTC);
    char buff[100];
    strftime(buff, sizeof buff, "%D %T", gmtime(&ts.tv_sec));
    printf("Current time: %s.%09ld UTC\n", buff, ts.tv_nsec);

Possible output:

Current time: 02/18/15 14:34:03.048508855 UTC


  • C17 standard (ISO/IEC 9899:2018):
    • The timespec_get function (p: 286)
  • C11 standard (ISO/IEC 9899:2011):
    • The timespec_get function (p: 390)

See also

time in seconds and nanoseconds
returns the resolution of calendar time based on a given time base
returns the current calendar time of the system as time since epoch
C++ documentation for timespec_get

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