php - 计算-1个月时的PHP天错误

Question

当我在PHP日期计算中遇到问题时，我感到惊讶。

$add = '- 30 days';
echo date('Y-m-01', strtotime($add)); // result is 2017-02-01 which is correct as need

但在

$add = '-1 month';
echo date('Y-m-01', strtotime($add)); // result is 2017-03-01 which is in correct

请帮我解决这个问题。

Answer 1

您可以看一下:http://php.net/manual/en/function.strtotime.php(说明和评论)

Note:

Using this function for mathematical operations is not advisable. It is better to use DateTime::add() and DateTime::sub() in PHP 5.3 and later, or DateTime::modify() in PHP 5.2.