http://drakecms.sf.net/index.php?option=content&id=32&Itemid=10
A short tutorial which explains how to consistently implement timezones with PHP4 while remaining forward compatible with PHP5.
date_default_timezone_set
说明
bool date_default_timezone_set ( string timezone_identifier )date_default_timezone_set() 设定用于所有日期时间函数的默认时区。
注意: 自 PHP 5.1.0 起（此版本日期时间函数被重写了），如果时区不合法则每个对日期时间函数的调用都会产生一条 E_NOTICE 级别的错误信息，如果使用系统设定或
TZ环境变量则还会产生 E_STRICT 级别的信息。
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User Contributed Notes
legolas558 d0t users dot sf dot net
10-Jun-2007 01:34
10-Jun-2007 01:34
PeerGoal.com
12-Feb-2007 12:21
12-Feb-2007 12:21
The problem:
date() [function.date]: It is not safe to rely on the system's timezone settings. Please use the date.timezone setting, the TZ environment variable or the date_default_timezone_set() function. In case you used any of those methods and you are still getting this warning, you most likely misspelled the timezone identifier. We selected 'America/Los_Angeles' for 'PST/-8.0/no DST' instead
Of course this is a problem that recently surfaced since PHP5. Quick fix is to set your time zone, add this line to your php code:
date_default_timezone_set("America/Los_Angeles");
davidn at datalinktech dot com dot au
22-Dec-2006 01:27
22-Dec-2006 01:27
Note that there may be some unexpected side-effects that result from using either set_default_timezone() or the putenv("TZ=...") workalike for earlier PHP versions. ANY date formatted and output either by PHP or its apache host process will be unconditionally expressed in that timezone.
This does indeed include the web server's logs and other output files and reports which by default usually do not include any indication of timezone. This has a further side-effect on log processing and analysis, obviously.
Chris
23-Nov-2006 06:14
23-Nov-2006 06:14
See the user contributed notes for the putenv function for a workaround for previous versions of PHP.