Re: gmmktime is broken [Bug #1529]

> The basic premise of the bug report is that I maintain that gmmktime is > broken. The last response I received was: > > > This is a documentation bug. The argument you pass to gmmktime is > > in local time, not GMT. The function would be useless, if you > > pass in GMT and get GMT out (you could use mktime for that). It's > > intended to be a conversion function from local time (in) to GMT > > (out). > > Is this true? This seems to be incorrect to me. If I pass gmmktime a > value of 0,0,0,1,1,1970 in my time zone (GMT -5), as the code stands, I > would get back a value of 36000 which is: Whoever wrote that in the bug database was confused. gmmktime() is indeed intended to be used as you say. Both mktime() and gmmktime() spit out stamdard unix timestamps. A unix timestamp is timezone neutral. There is no timezone attached to them at all. Timezones are applied when it comes time to convert the timestamp to something readable. If you look at the _php3_mktime() function in functions/datetime.c in the PHP source code, you will see the following snippet of code: #if HAVE_TZSET tzset(); #endif tn = localtime(&t); if (gm) { #if HAVE_TM_GMTOFF gmadjust=(tn->tm_gmtoff)/3600; #else gmadjust=timezone/3600; #endif } The 'gm' variable is set when you call the function as gmmktime() and it calculates a local timezone adjustment factor for your location. This adjustment factor is applied to the hour argument in the gmmktime() call with this line: ta.tm_hour = arguments[0]->value.lval - gmadjust; So, in my timezone (EDT) my gmadjust is current -4, so if I pass gmmktime() a timestamp of noon, it adjusts it by adding 4 hours to it. That is, it converts the arguments I feed gmmktime() from GMT to my local timezone (would probably fail in the weird .5 timezones, but we'll fix that some other day). But, this is also where your bug comes in. That adjustment line should be: ta.tm_hour = arguments[0]->value.lval + gmadjust; Try making that change. The one slight weirdness here is that I think the adjustment doesn't take daylight savings time into account. I don't have time to look into that right now. Play around with it. -Rasmus