NAME

daylight, timezone, tzname, tzset - set timezone conversion information

SYNOPSIS

#include <time.h>



[XSI] extern int daylight;
extern long timezone;


[CX] extern char *tzname[2];
void tzset(void);

DESCRIPTION

The tzset() function shall use the value of the environment variable TZ to set time conversion information used by ctime() , localtime() , mktime() , and strftime() . If TZ is absent from the environment, implementation-defined default timezone information shall be used.

The tzset() function shall set the external variable tzname as follows:

tzname[0] = "std";
tzname[1] = "dst";

where std and dst are as described in the Base Definitions volume of IEEE Std 1003.1-2001, Chapter 8, Environment Variables.

^[XSI] The tzset() function also shall set the external variable daylight to 0 if Daylight Savings Time conversions should never be applied for the timezone in use; otherwise, non-zero. The external variable timezone shall be set to the difference, in seconds, between Coordinated Universal Time (UTC) and local standard time.

RETURN VALUE

The tzset() function shall not return a value.

ERRORS

No errors are defined.

EXAMPLES

Example TZ variables and their timezone differences are given in the table below:

TZ	timezone
EST5EDT	5*60*60
GMT0	0*60*60
JST-9	-9*60*60
MET-1MEST	-1*60*60
MST7MDT	7*60*60
PST8PDT	8*60*60

APPLICATION USAGE

None.

RATIONALE

None.

FUTURE DIRECTIONS

None.

SEE ALSO

ctime() , localtime() , mktime() , strftime() , the Base Definitions volume of IEEE Std 1003.1-2001, Chapter 8, Environment Variables, <time.h>

CHANGE HISTORY

First released in Issue 1. Derived from Issue 1 of the SVID.

Issue 6

The example is corrected.