gettimeofday(), gettimeofday64() — Get date and time

Standards

Standards / Extensions C or C++ Dependencies
XPG4.2
Single UNIX Specification, Version 3
Language Environment®
 both  

Format

#define _XOPEN_SOURCE_EXTENDED 1

#undef _ALL_SOURCE
#include <sys/time.h>

int gettimeofday(struct timeval *__restrict__ tp,
                 void *__restrict__ tzp);

#define _ALL_SOURCE
#include <sys/time.h>

int gettimeofday(struct timeval *__restrict__ tp, 
                 struct timezone *__restrict__ tzp);
#define _LARGE_TIME_API
#include <time.h>

int gettimeofday64(struct timeval64 *__restrict__ tp,  
                   void *__restrict__ tzp);

General description

The gettimeofday() function obtains the current time, expressed as seconds and microseconds since 00:00:00 Coordinated Universal Time (UTC), January 1, 1970, and stores it in the timeval structure pointed to by tp.

Special behavior for _ALL_SOURCE: The gettimeofday() function has two prototypes. Which one is used depends on whether or not you define the _ALL_SOURCE feature test macro when you compile your program. If _ALL_SOURCE is NOT defined when the C/370 preprocessor processes the <sys/time.h> header, it includes a prototype for gettimeofday() which defines the second argument, tzp, as a void pointer and includes a C/370 pragma map statement for a C/370 version of gettimeofday() which ignores tzp.

If _ALL_SOURCE is defined, the C/370 preprocessor includes a prototype for gettimeofday() which defines tzp as a pointer to a timezone structure and includes a pragma map statement for a C/370 version of gettimeofday() which stores time zone information in the timezone structure to which the second argument points. The timezone structure contains the following members: 
     int tz_minuteswest;   /* Time west of Greenwich in minutes */
     int tz_dsttime;       /* Type of DST correction to apply   */
When _ALL_SOURCE is defined, the gettimeofday() function:
  1. invokes tzset() to set the values of the timezone and daylight external variables.
  2. converts the value of the timezone external variable to minutes and stores the converted value, rounded up to the nearest minute, in tzp->tz_minuteswest.
  3. stores the value of the daylight external variable in tzp->tz_dsttime.

The function gettimeofday64() will behave exactly like gettimeofday() except it will support calendar times beyond 03:14:07 UTC on January 19, 2038.

There is no support for an _ALL_SOURCE version of gettimeofday64().

Returned value

If successful, gettimeofday() returns 0.

If overflow occurs, gettimeofday() returns nonzero. Overflow occurs when the current time in seconds since 00:00:00 UTC, January 1, 1970 exceeds the capacity of the tv_sec member of the timeval structure pointed to by tp. The tv_sec member is type time_t.

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