tzfile(5)tzfile(5)Nametzfile - time zone information
Syntax
#include <tzfile.h>
Description
The time zone information files used by begin with bytes reserved for
future use, followed by three 4-byte values of type ``long'', written
in a ``standard'' byte order (the high-order byte of the value is writ‐
ten first). These values are, in order:
tzh_timecnt The number of transition times for which data is stored
in the file.
tzh_typecnt The number of local time types for which data is stored
in the file (must not be zero).
tzh_charcnt The number of characters of ``time zone abbreviation
strings'' stored in the file.
This header is followed by 4-byte values of type
``long'', sorted in ascending order. These values are
written in ``standard'' byte order. Each is used as a
transition time (as returned by at which the rules for
computing local time change). Next come 1-byte values
of type ``unsigned char''. Each one tells which of the
different types of local time types described in the
file is associated with the same-indexed transition
time. These values serve as indices into an array of
ttinfo structures that appears next in the file; these
structures are defined as follows:
struct ttinfo {
long tt_gmtoff;
int tt_isdst;
unsigned int tt_abbrind;
};
Each structure is written as a 4-byte value for of type
``long'', in a standard byte order, followed by a 1-byte
value for and a 1-byte value for In each structure,
gives the number of seconds to be added to GMT, tells
whether should be set by and serves as an index into the
array of time zone abbreviation characters that follows
the structure or structures in the file.
The call uses the first standard-time structure in the file (or simply
the first structure, in the absence of a standard-time structure) if
either is zero or the time argument is less than the first transition
time recorded in the file.
See Alsoctime(3)tzfile(5)
