time_t

typedef /* unspecified */ time_t;

Arithmetic (until C11) Real (since C11) type capable of representing times.

Although not defined by the C standard, this is almost always an integral value holding the number of seconds (not counting leap seconds) since 00:00, Jan 1 1970 UTC, corresponding to POSIX time.

Notes

The standard uses the term calendar time when referring to a value of type time_t.

Example

#include <stdio.h>
#include <time.h>
#include <stdint.h>
 
int main(void)
{
    time_t epoch = 0;
    printf("%jd seconds since the epoch began\n", (intmax_t)epoch);
    printf("%s", asctime(gmtime(&epoch)));
}

0 seconds since the epoch began
Thu Jan  1 00:00:00 1970

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)
• C99 standard (ISO/IEC 9899:1999):
• 7.23.1/3 Components of time (p: 338)
• C89/C90 standard (ISO/IEC 9899:1990):
• 4.12.1 Components of time

See also