time

Defined in header `<time.h>`
time_t time( time_t *arg );

Returns the current calendar time encoded as a time_t object, and also stores it in the time_t object pointed to by arg (unless arg is a null pointer)

Parameters

arg

-

pointer to a time_t object where the time will be stored, or a null pointer

Return value

Current calendar time encoded as time_t object on success, (time_t)(-1) on error. If arg is not a null pointer, the return value is also stored in the object pointed to by arg.

Notes

The encoding of calendar time in time_t is unspecified, but most systems conform to POSIX specification and return a value of integral type holding the number of seconds since the Epoch. Implementations in which time_t is a 32-bit signed integer (many historical implementations) fail in the year 2038.

Example

Run this code

#include <stdio.h>
#include <time.h>
#include <stdint.h>
 
int main(void)
{
    time_t result = time(NULL);
    if(result != (time_t)(-1))
        printf("The current time is %s(%jd seconds since the Epoch)\n",
               asctime(gmtime(&result)), (intmax_t)result);
}

Possible output:

The current time is Fri Apr 24 15:05:25 2015
(1429887925 seconds since the Epoch)

References

C17 standard (ISO/IEC 9899:2018):

7.27.2.4 The time function (p: 286)

C11 standard (ISO/IEC 9899:2011):

7.27.2.4 The time function (p: 391)

C99 standard (ISO/IEC 9899:1999):

7.23.2.4 The time function (p: 341)

C89/C90 standard (ISO/IEC 9899:1990):

4.12.2.4 The time function

Language
Headers
Type support
Program utilities
Variadic function support
Error handling
Dynamic memory management
Date and time utilities
Strings library
Algorithms
Numerics
Input/output support
Localization support
Atomic operations (C11)
Thread support (C11)
Technical Specifications

Functions
Time manipulation
difftime
time
clock
timespec_get (C11)
timespec_getres (C23)
Format conversions
asctimeasctime_rasctime_s (C23)(C11)
ctimectime_rctime_s (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)

localtimelocaltime_rlocaltime_s (C23)(C11)	converts time since epoch to calendar time expressed as local time (function)
gmtimegmtime_rgmtime_s (C23)(C11)	converts time since epoch to calendar time expressed as Coordinated Universal Time (UTC) (function)
timespec_get (C11)	returns the calendar time based on a given time base (function)