std-unix@ut-sally.UUCP (12/13/86)
References:
From: utah-cs!hplabs!hpfcla!hpfclj!hpfcdg!rgt (Ron Tolley)
Date: Wed, 10 Dec 86 18:51:58 est
The HP proposal boils down to five changes to the RFC.001 Timezone
Interface by Robert Elz. I have listed these in order of importance
with exception of the first (which is really just a change to a
comment). As it turns out they are also in the order that they would
appear in RFC.001.
[ RFC.001 has been superseded by P.55, which I reposted recently. -mod ]
<(1) Replace (if it makes any difference) the paragraph>
So, I'm going to propose something that could be inserted into
P1003 (with the obvious extra definitions that I'm going to
leave out on the assumption that everyone knows what they are,
like the definition of the struct "tm").
<with the paragraph>
So, I'm going to propose something that could be inserted into
P1003 (with the obvious extra definitions that I'm going to
leave out on the assumption that everyone knows what they are.)
<(2) Replace the paragraph>
Implementations shall provide the following functions:
struct tm *gmtime(t) time_t *t;
struct tm *localtime(t) time_t *t;
int settz(p) char *p;
char *asctime(tp) struct tm *tp;
char *ctime(t) time_t *t;
<with the following paragraphs>
The "tm" structure shall be defined as:
struct tm {
int tm_sec; /\(** seconds (0 - 59) \(**/
int tm_min; /\(** minutes (0 - 59) \(**/
int tm_hour; /\(** hours (0 - 23) \(**/
int tm_mday; /\(** day of month (1 - 31) \(**/
int tm_mon; /\(** month of year (0 - 11) \(**/
int tm_year; /\(** year \- 1900 \(**/
int tm_wday; /\(** day of week (Sunday = 0) \(**/
int tm_yday; /\(** day of year (0 - 365) \(**/
int tm_isdst; /\(** is DST in effect? \(**/
long tm_tzadj; /\(** time zone adjustment \(**/
char *tm_tnptr; /\(** points to time zone name \(**/
};
where tm_isdst is non-zero if a time zone adjustment such as Daylight
Savings Time is in effect, tm_tzadj is the difference between GMT and
local time expressed in seconds, and tm_tnptr points to a string
containing the time zone abbreviation.
The tm_isdst, tm_tzadj, and tm_tnptr members of the tm structure may be
viewed as equivalents to the daylight, timezone, and tzname[] external
variables however their values track those in the rest of the tm
structure.
Implementations shall provide the following functions:
struct tm *gmtime(t) time_t *t;
struct tm *localtime(t) time_t *t;
int settz(p) char *p;
char *asctime(tp) struct tm *tp;
char *ctime(t) time_t *t;
int strftime (p, n, f, tp) char *p, int n, char *f, struct tm *tp;
int strctime (p, n, f, t) char *p, int n, char *f, time_t *t;
time_t mktime (tp) struct tm *tp;
<(3) Add after the paragraph describing ctime the following paragraphs>
strftime: supports formatted output of date and time, according to a
user-supplied format string. Locale-specific values such as month and
weekday names are provided according to the currently defined locale.
(The method of setting locale will be addressed elsewhere. The
setlocale or nl_init routines are currently available in some
implementations.) Strftime limits the length of the return string p to
be no greater than n characters (including the terminating null
character). The actual number of characters (excluding the null
character) included in p is returned by each successful call. Unlike
asctime, no newline is automatically appended to the formatted string.
strctime: also supports formatting but takes time_t *t as an argument.
format: uses field descriptors similar to those in the first argument
to printf(3S). Numeric output fields are of fixed size (zero padded if
necessary). All other characters are copied to the output without
change. Field descriptors are expanded as follows:
%a is replaced by the abbreviated weekday name
%A is replaced by the full weekday name
%b is replaced by the abbreviated month name
%B is replaced by the full month name
%c is replaced by the appropriate date and time representation
%d is replaced by the day of the month as a decimal number (01
to 31)
%H is replaced by the hour (24-hour clock) as a decimal number
(00 to 23)
%I is replaced by the hour (12-hour clock) as a decimal number
(01 to 12)
%j is replaced by the day of the year as a decimal number (001
to 366)
%m is replaced by the month as a decimal number (01 to 12)
%M is replaced by the minute as a decimal number (00 to 59)
%n is replaced by a new-line character
%p is replaced by the equivalent of AM or PM
%r is replaced by the appropriate (12-hour clock) time
representation
%S is replaced by seconds as a decimal number (00 to 59)
%t is replaced by a tab character
%U is replaced by the week number of the year with Sunday as the
first day of the week (00 to 52)
%V is replaced by the week number of the year with Monday as the
first day of the week (00 to 52)
%w is replaced by the weekday as a decimal number [0 (Sunday) to 6]
%x is replaced by the appropriate date representation
%X is replaced by the appropriate time representation
%y is replaced by the year without century (00 to 99)
%Y is replaced by the year with century
%Z is replaced by the time zone name
%% is replaced by %
<(4) Add the following paragraph after those mentioned in (3)>
mktime: computes a long integer time value from a time value contained
in a "tm" structure. The values of tm_wday and tm_yday are overwritten
during this computation.
<(5) Remove all references to settz(). Localtime will use the value of TZ
to determine the what local time means. If TZ is not set, then localtime
will return a best guess at localtime.>
Ron Tolley
Volume-Number: Volume 8, Number 65