timespec

 

C

Language

Headers

Type support

Program utilities

Variadic function support

Error handling

Dynamic memory management

Strings library

Algorithms

Numerics

Date and time utilities

Input/output support

Localization support

Concurrency support (C11)

Technical Specifications

Symbol index

 

Date and time utilities

Functions

Time manipulation

difftime

time

clock

timespec_get (C11)

timespec_getres (C23)

Format conversions

asctimeasctime_s (deprecated in C23)(C11)

ctimectime_s (deprecated in C23)(C11)

strftime

wcsftime (C95)

gmtimegmtime_rgmtime_s (C23)(C11)

localtimelocaltime_rlocaltime_s (C23)(C11)

mktime

Constants

CLOCKS_PER_SEC

Types

tm

time_t

clock_t

timespec (C11)

 

Defined in header <time.h>
struct timespec;		(since C11)

Structure holding an interval broken down into seconds and nanoseconds.

Member objects

time_t tv_sec	whole seconds (valid values are >= 0)
/* see below */ tv_nsec	nanoseconds (valid values are [0, 999999999])

The type of tv_nsec is long.	(until C23)
The type of tv_nsec is an implementation-defined signed integer type that can represent integers in [0, 999999999].	(since C23)

The declaration order of tv_sec and tv_nsec is unspecified. Implementation may add other members to struct timespec.

Notes

The type of tv_nsec is long long on some platforms, which is conforming only since C23.

Example

Run this code

#include <stdio.h>
#include <time.h>
#include <stdint.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);
    printf("Raw timespec.time_t: %jd\n", (intmax_t)ts.tv_sec);
    printf("Raw timespec.tv_nsec: %09ld\n", ts.tv_nsec);
}

Possible output:

Current time: 11/24/21 03:10:50.408191283 UTC
Raw timespec.time_t: 1637723450
Raw timespec.tv_nsec: 408191283

References

• C17 standard (ISO/IEC 9899:2018):

• 7.27.1/3 Components of time (p: 284)

• C11 standard (ISO/IEC 9899:2011):

• 7.27.1/3 Components of time (p: 388)

See also

timespec_get (C11)	returns the calendar time in seconds and nanoseconds based on a given time base (function)
tm	calendar time type (struct)