Time confusion?

[John W. Eaton]

On 10-Mar-2004, Vic Norton <address@hidden> wrote:

| Maybe this is a bug. Maybe it isn't. In any case, it is very 
| confusing. I'm talking about the relationship between time structures 
| and the functions strptime, strftime, and mktime.
| 
| Start with the date 23-Feb-04. That was a Monday. Do strptime to get 
| a TM_STRUCT and then do strftime to that. This changes the day. Now 
| 23-Feb-04 is Sunday.
| 
| OK, let's get down to real time. Do mktime to the TM_STRUCT to see 
| that the 23-Feb-04 date is 1077512400 seconds after after 1-Jan-1970 
| 00:00:00 CUT. (1077512400 is also the time I get from the str2time 
| function in the Date::Parse perl module.) Now do localtime to 
| 1077512400 and strftime to the resulting TM_STRUCT to find out that 
| 23-Feb-04 is back to Monday.
| 
| Something is very strange here. One date just can't be on two different days!
| 
| Regards,
| 
| Vic
| 
| P.S. Here is the test and the output.
| 
| === test ===
| % test1.m
| 
| date0 = '23-Feb-04'
| tm_struct1 = strptime(date0, "%e-%b-%y")
| date1 = strftime("%a, %e-%b-%y", tm_struct1)
| time1 = mktime(tm_struct1)
| tm_struct2 = localtime(time1)
| date2 = strftime("%a, %e-%b-%y", tm_struct2)
| 
| === output ===
| octave> test1
| date0 = 23-Feb-04
| tm_struct1 =
| {
|    hour = 0
|    isdst = 0
|    mday = 23
|    min = 0
|    mon = 1
|    sec = 0
|    usec = 0
|    wday = 0
|    yday = 0
|    year = 104
|    zone =
| }
| 
| date1 = Sun, 23-Feb-04
| time1 = 1077512400
| tm_struct2 =
| {
|    hour = 0
|    isdst = 0
|    mday = 23
|    min = 0
|    mon = 1
|    sec = 0
|    usec = 0
|    wday = 1
|    yday = 53
|    year = 104
|    zone = EST
| }
| 
| date2 = Mon, 23-Feb-04

What version of Octave are you using?  I don't see this problem with
the current sources.  I seem to remember fixing a bug that could have
been related to this problem, but I don't remember precisely what it
was and I can't find a message about it in the archives.

jwe



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