tzname contains two strings, which are the standard
names of the pair of time zones (standard and Daylight
Saving) that the user has selected.
tzname is the name of
the standard time zone (for example,
is the name for the time zone when Daylight Saving Time is in use (for
"EDT"). These correspond to the std and dst
strings (respectively) from the
TZ environment variable. If
Daylight Saving Time is never used,
tzname is the empty string.
tzname array is initialized from the
localtime is called. If multiple abbreviations
have been used (e.g.
"EDT" for U.S. Eastern War
Time and Eastern Daylight Time), the array contains the most recent
tzname array is required for POSIX.1 compatibility, but in
GNU programs it is better to use the
tm_zone member of the
broken-down time structure, since
tm_zone reports the correct
abbreviation even when it is not the latest one.
Though the strings are declared as
char * the user must refrain
from modifying these strings. Modifying the strings will almost certainly
lead to trouble.