time

Get time of day

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Contents

Interface
Description
Errors
See Also
Standards
Bugs
History
Page Comments

Interface

#include <time.h>time_t  time (time_t *tloc)

Description

The time function returns the value of time in seconds since 0 hours, 0 minutes, 0 seconds, January 1, 1970, Coordinated Universal Time, without including leap seconds. If an error occurs, time returns the value time_t - 1.

The return value is also stored in * tloc, provided that tloc is non-null.

Example:

Example - Get time of day

Workings

#include <stdio.h>
#include <time.h>
int main ()
{
  printf ("%ld hours since January 1, 1970\n", time(0)/3600);  
  return 0;
}

Solution

Output:

339479 hours since January 1, 1970

Errors

The time function may fail for any of the reasons described in gettimeofday.

Standards

The time function conforms to IEEE Std 1003.1-2001 ("POSIX.1").

Bugs

Neither ISO/IEC 9899:1999 ("ISO C99") nor IEEE Std 1003.1-2001 ("POSIX.1") requires time to set errno on failure; thus, it is impossible for an application to distinguish the valid time value -1 (representing the last UTC second of 1969) from the error return value.

Systems conforming to earlier versions of the C and POSIX standards (including older versions of FreeBSD) did not set * tloc in the error case.

History

A time function appeared in Version 6 AT&T UNIX.

Page Comments

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