PHP - DateTime diff（）显示两个日期的0个月，一年差异？

Question

I was running a quick test to help a co-worker with a problem related to dates in PHP using the DateTime object.

Surprisingly, when I run this piece of code:

namespace Tests\DateTime {
    $date1 = new \DateTime("2013-01-01", new \DateTimeZone("UTC"));
    $date2 = new \DateTime("2014-01-01", new \DateTimeZone("UTC"));
    $interval = $date1->diff($date2);
    print $interval->m;
}

I get 0 as the return value. When you use it to measure the different between those two dates within the same year, everything works fine. 1,2,3,4,5, ..., 11 months difference from January to December.

Why is it happening?

Answer 1

I think you're getting zero because you're only printing the difference in months. You likely want to run your interval through DateInterval::format .