note 38068 added to function.mktime

If you want to calculate dates before 1970 and your OS doesn't support it (Windows and Linux), you can easily write your own wrapper to mktime to do the calculation. The idea is to find a date range in the 1970-2037 time frame that is the same as your year prior to 1970 (both years start on the same day of the week and leap years are the same), then add that number of years to your year value before calling mktime() and then subtract the corresponding number of seconds from the mktime() result (including the appropriate number of leap seconds). This way old guys like me (born in 1963) can get a valid number back from mktime() and we can figure out how old we are in seconds. :-) You can go all the way back to 1902 if you want. The mapping is as follows: 1902-1951 = 1986-2035 1952-1969 = 1980-1997 By matching starting day of week for the year and leap years then we should calculate daylight time correctly (assuming that we have the right rules set). There's a special hack in the code to turn off daylight time prior to 1942 for date(). Here's the code that we're using now: // // Replacement for mktime that does dates before 1970 // function MakeTime() { $objArgs = func_get_args(); $nCount = count($objArgs); if ($nCount < 7) { $objDate = getdate(); if ($nCount < 1) $objArgs[] = $objDate["hours"]; if ($nCount < 2) $objArgs[] = $objDate["minutes"]; if ($nCount < 3) $objArgs[] = $objDate["seconds"]; if ($nCount < 4) $objArgs[] = $objDate["mon"]; if ($nCount < 5) $objArgs[] = $objDate["mday"]; if ($nCount < 6) $objArgs[] = $objDate["year"]; if ($nCount < 7) $objArgs[] = -1; } $nYear = $objArgs[5]; $nOffset = 0; if ($nYear < 1970) { if ($nYear < 1902) return 0; else if ($nYear < 1952) { $nOffset = -2650838400; $objArgs[5] += 84; // Apparently dates before 1942 were never DST if ($nYear < 1942) $objArgs[6] = 0; } else { $nOffset = -883612800; $objArgs[5] += 28; } } return call_user_func_array("mktime", $objArgs) + $nOffset; } In Linux, the values returned will work just fine with date() and I believe that strftime() should work too, but Windows doesn't like the negative values at all. We had to write a replacement for strtotime since it appears to call mktime() to come up with the final result. I hope that this helps someone. - todd ---- Manual Page -- http://www.php.net/manual/en/function.mktime.php Edit -- http://master.php.net/manage/user-notes.php?action=edit+38068 Delete -- http://master.php.net/manage/user-notes.php?action=delete+38068&report=yes Reject -- http://master.php.net/manage/user-notes.php?action=reject+38068&report=yes Search -- http://master.php.net/manage/user-notes.php