# timespec

From cppreference.com
< c‎ | chrono

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)

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