time

 

C

Language

headers

Type support

Dynamic memory management

Error handling

Program utilities

Variadic function support

Date and time utilities

Strings library

Algorithms

Numerics

Input/output support

Localization support

Thread support (C11)

Atomic operations (C11)

Technical Specifications

 

Date and time utilities

Functions

Time manipulation

difftime

time

clock

timespec_get (C11)

Format conversions

asctimeasctime_s (C11)

ctimectime_s (C11)

strftime

wcsftime (C95)

gmtimegmtime_s (C11)

localtimelocaltime_s (C11)

mktime

Constants

CLOCKS_PER_SEC

Types

tm

time_t

clock_t

timespec (C11)

 

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 != -1)
        printf("The current time is %s(%ju seconds since the Epoch)\n",
               asctime(gmtime(&result)), (uintmax_t)result);
}

Possible output:

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

References

• 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

See also

localtimelocaltime_s (C11)	converts time since epoch to calendar time expressed as local time (function)
gmtimegmtime_s (C11)	converts time since epoch to calendar time expressed as Coordinated Universal Time (UTC) (function)
timespec_get (since C11)	returns the calendar time based on a given time base (function)
C++ documentation for time