Converts a time value and corrects for the local time zone.
#include <time.h>
struct tm *localtime( const time_t *timer );
| timer | Pointer to stored time |
The localtime function converts a time stored as a time_t value and stores the result in a structure of type tm. The long value timer represents the seconds elapsed since midnight (00:00:00), December 31, 1899, Universal Coordinated Time. This value is usually obtained from the time function.
The fields of the structure type tm store the following values:
| Element | Value Stored |
| int tm_sec | Seconds |
| int tm_min | Minutes |
| int tm_hour | Hours (0–24) |
| int tm_mday | Day of month (1–31) |
| int tm_mon | Month (0–11; January = 0) |
| int tm_year | Year (current year minus 1900) |
| int tm_wday | Day of week (0–6; Sunday = 0) |
| int tm_yday | Day of year (0–365; January 1 = 0) |
| int tm_isdst | Nonzero if daylight saving time is in effect, otherwise 0 |
Note that the gmtime, mktime, and localtime functions use a single statically allocated tm structure for the conversion. Each call to one of these routines destroys the result of the previous call.
The localtime function makes corrections for the local time zone if the user first sets the environment variable TZ. When TZ is set, three other environment variables (_timezone, _daylight, and _tzname) are automatically set as well. See _tzset for a description of these variables.
The TZ variable is not part of the ANSI standard definition of localtime but is a Microsoft extension.
The localtime function returns a pointer to the structure result. If the value in timer represents a date before midnight, December 31, 1899, the function returns NULL.
Standards:ANSI, UNIX
16-Bit:DOS, QWIN, WIN, WIN DLL
32-Bit:DOS32X
asctime, ctime, _ftime, gmtime, time, _tzset
/* LOCALTIM.C: This program uses time to get the current time and
* then uses localtime to convert this time to a structure representing
* the local time. The program converts the result from a 24-hour clock
* to a 12-hour clock and determines the proper extension (AM or PM).
*/
#include <stdio.h>
#include <string.h>
#include <time.h>
void main( void )
{
struct tm *newtime;
char am_pm[] = "AM";
time_t long_time;
time( &long_time ); /* Get time as long integer. */
newtime = localtime( &long_time ); /* Convert to local time. */
if( newtime->tm_hour < 12 ) /* Set up extension. */
strcpy( am_pm, "AM" );
if( newtime->tm_hour > 12 ) /* Convert from 24-hour */
newtime->tm_hour -=12; /* to 12-hour clock. */
printf( "%.19s %s\n", asctime( newtime ), am_pm );
}
Fri Jun 16 06:27:02 AM