daylight, timezone, tzname, tzset - set timezone conversion information
#include <time.h>
[XSI] extern int daylight;
extern long timezone;
[CX] extern char *tzname[2];
void tzset(void);
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.
The tzset() function shall not return a value.
No errors are defined.
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
None.
None.
None.
ctime(), localtime(), mktime(), strftime(), the Base Definitions volume of IEEE Std 1003.1-2001, Chapter 8, Environment Variables, <time.h>
First released in Issue 1. Derived from Issue 1 of the SVID.
The example is corrected.