php - 获取上个月第一天的结果变化

Question

尝试获取上个月的第一天和最后一天:

 $monthStart = new DateTime("first day of last month");
 $monthEnd = new DateTime("last day of last month");

 $sMonth = $monthStart->format('U');
 $eMonth = $monthEnd->format('U');

 echo $sMonth . "," . $eMonth;

结果:

 1485968094,1488300894

2 秒后做同样的事情:

 1485968096,1488300896

56 秒后做同样的事情:

 1485968151,1488300951 

为什么这些值会改变？我每次都会期待以下内容:

 1485907200,1488240000 (for feb 2017)

Answer 1

您需要明确设置时间:

$monthStart = (new DateTime("first day of last month"))->setTime(0,0,0);
$monthEnd = (new DateTime("last day of last month"))->setTime(23,59,59);

默认返回当前时间。