time, _time32, _time64 (2024)

Article
02/13/2023

Syntax

time_t time( time_t *destTime );__time32_t _time32( __time32_t *destTime );__time64_t _time64( __time64_t *destTime );

Parameters

destTime
Pointer to the storage location for time.

Return value

Returns the time as seconds elapsed since midnight, January 1, 1970, or -1 if there's an error.

Remarks

The time function returns the number of seconds elapsed since midnight (00:00:00), January 1, 1970, Coordinated Universal Time (UTC), according to the system clock. The return value is stored in the location given by destTime. This parameter may be NULL, in which case the return value isn't stored.

time is a wrapper for _time64 and time_t is, by default, equivalent to __time64_t. If you need to force the compiler to interpret time_t as the old 32-bit time_t, you can define _USE_32BIT_TIME_T. We don't recommend _USE_32BIT_TIME_T, because your application may fail after January 18, 2038; the use of this macro isn't allowed on 64-bit platforms.

Requirements

Routine	Required C header	Required C++ header
`time`, `_time32`, `_time64`	`<time.h>`	`<ctime>` or `<time.h>`

For more compatibility information, see Compatibility.

Example

// crt_times.c// compile with: /W3// This program demonstrates these time and date functions:// time _ftime ctime_s asctime_s// _localtime64_s _gmtime64_s mktime _tzset// _strtime_s _strdate_s strftime//// Also the global variable:// _tzname//// Turn off deprecated unsafe CRT function warnings#define _CRT_SECURE_NO_WARNINGS 1#include <time.h>#include <stdio.h>#include <stdlib.h>#include <sys/types.h>#include <sys/timeb.h>#include <string.h>int main(){ char tmpbuf[128], timebuf[26], ampm[] = "AM"; time_t ltime; struct _timeb tstruct; struct tm today, gmt, xmas = { 0, 0, 12, 25, 11, 93 }; errno_t err; // Set time zone from TZ environment variable. If TZ is not set, // the operating system is queried to obtain the default value // for the variable. // _tzset(); // Display operating system-style date and time. _strtime_s( tmpbuf, 128 ); printf( "OS time:\t\t\t\t%s\n", tmpbuf ); _strdate_s( tmpbuf, 128 ); printf( "OS date:\t\t\t\t%s\n", tmpbuf ); // Get UNIX-style time and display as number and string. time( &ltime ); printf( "Time in seconds since UTC 1/1/70:\t%lld\n", (long long)ltime ); err = ctime_s(timebuf, 26, &ltime); if (err) { printf("ctime_s failed due to an invalid argument."); exit(1); } printf( "UNIX time and date:\t\t\t%s", timebuf ); // Display UTC. err = _gmtime64_s( &gmt, &ltime ); if (err) { printf("_gmtime64_s failed due to an invalid argument."); } err = asctime_s(timebuf, 26, &gmt); if (err) { printf("asctime_s failed due to an invalid argument."); exit(1); } printf( "Coordinated universal time:\t\t%s", timebuf ); // Convert to time structure and adjust for PM if necessary. err = _localtime64_s( &today, &ltime ); if (err) { printf("_localtime64_s failed due to an invalid argument."); exit(1); } if ( today.tm_hour >= 12 ) { strcpy_s( ampm, sizeof(ampm), "PM" ); today.tm_hour -= 12; } if ( today.tm_hour == 0 ) // Adjust if midnight hour. today.tm_hour = 12; // Convert today into an ASCII string err = asctime_s(timebuf, 26, &today); if (err) { printf("asctime_s failed due to an invalid argument."); exit(1); } // Note how pointer addition is used to skip the first 11 // characters and printf is used to trim off terminating // characters. // printf( "12-hour time:\t\t\t\t%.8s %s\n", timebuf + 11, ampm ); // Print additional time information. _ftime( &tstruct ); // C4996 // Note: _ftime is deprecated; consider using _ftime_s instead printf( "Plus milliseconds:\t\t\t%u\n", tstruct.millitm ); printf( "Zone difference in hours from UTC:\t%u\n", tstruct.timezone/60 ); printf( "Time zone name:\t\t\t\t%s\n", _tzname[0] ); //C4996 // Note: _tzname is deprecated; consider using _get_tzname printf( "Daylight savings:\t\t\t%s\n", tstruct.dstflag ? "YES" : "NO" ); // Make time for noon on Christmas, 1993. if( mktime( &xmas ) != (time_t)-1 ) { err = asctime_s(timebuf, 26, &xmas); if (err) { printf("asctime_s failed due to an invalid argument."); exit(1); } printf( "Christmas\t\t\t\t%s\n", timebuf ); } // Use time structure to build a customized time string. err = _localtime64_s( &today, &ltime ); if (err) { printf(" _localtime64_s failed due to invalid arguments."); exit(1); } // Use strftime to build a customized time string. strftime( tmpbuf, 128, "Today is %A, day %d of %B in the year %Y.\n", &today ); printf( tmpbuf );}

OS time: 13:51:23OS date: 04/25/03Time in seconds since UTC 1/1/70: 1051303883UNIX time and date: Fri Apr 25 13:51:23 2003Coordinated universal time: Fri Apr 25 20:51:23 200312-hour time: 01:51:23 PMPlus milliseconds: 552Zone difference in hours from UTC: 8Time zone name: Pacific Standard TimeDaylight savings: YESChristmas Sat Dec 25 12:00:00 1993Today is Friday, day 25 of April in the year 2003.