strtotime在不同的PHP版本上返回不同的结果

Question

I came across a weird problem with strtotime function returning different (and I think incorrect) results.

This is my test code and results:

$fromTime = strtotime('2013-10-22');
$toTime = strtotime('2013-10-28');
$days = ($toTime - $fromTime) / (3600 * 24);

var_dump($days, $fromTime, $toTime);

// PHP 5.2.5 on codepad.org - correct
// int(6)
// int(1382400000)
// int(1382918400)

// PHP 5.3.15, PHP 5.4.6 - incorrect I guess
// float(6.0416666666667)
// int(1382392800)
// int(1382914800)

You can see it live on http://codepad.org/gdTqFLqG .
Do you have any idea why is this happening?

Answer 1

I agree with @NB's suggestion to use the DateTime class instead -- You shouldn't really be using strtotime() for this kind of thing today.

However, as for why it's happening, look at the dates you're comparing.... what often happens between those dates? Yep, that's right -- daylight savings.

So my guess is that it's got nothing to do with the PHP version, and more to do with the timezone setup on the different platforms you're testing. One is set to use the UCT and the other is set to use a local timezone that has DST.

Answer 2

您应该使用date_default_timezone_set（），因为在第二次测试中您通过一些UTC +-校正获得了正确的时间。