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_daylight, _dstbias, _timezone, and _tzname 

_daylight, _dstbias, _timezone, and _tzname are used in some time and date routines to make local-time adjustments. These global variables have been deprecated in Visual C++ 2005 for the more secure functional versions, which should be used in place of the global variables.

Global variable Functional equivalent

_daylight

_get_daylight

_dstbias

_get_dstbias

_timezone

_get_timezone

_tzname

_get_tzname

They are declared in Time.h as follows.


extern int _daylight; 
extern int _dstbias; 
extern long _timezone; 
extern char *_tzname[2];

On a call to _ftime, localtime, or _tzset, the values of _daylight, _dstbias, _timezone, and _tzname are determined from the value of the TZ environment variable. If you do not explicitly set the value of TZ, _tzname[0] and _tzname[1] contain the default settings of "PST" and "PDT" respectively. The time-manipulation functions (_tzset, _ftime, and localtime) attempt to set the values of _daylight, _dstbias and _timezone by querying the operating system for the default value of each variable. The time-zone global variable values are shown in the following table.

Variable Value

_daylight

Nonzero if daylight saving time (DST) zone is specified in TZ or determined from the operating system; otherwise, 0. The default value is 1.

_dstbias

Offset for daylight saving time.

_timezone

Difference in seconds between coordinated universal time and local time. The default value is 28,800.

_tzname[0]

Time-zone name derived from the TZ environment variable. The default value is "PST".

_tzname[1]

DST zone name derived from the TZ environment variable. The default value is "PDT" (Pacific daylight time).

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