cal_days_in_month(）[function.cal days in month]:无效日期 - cal_days_in_month() [function.cal-days-in-month]: invalid date

cal_days_in_month() [function.cal-days-in-month]: invalid date

我想计算一个月的天数。它出现了这个警告：

cal_days_in_month() [function.cal-days-in-month]: invalid date.

有人能帮我吗

$numberofday = new DateTime($month);
$numberofday = cal_days_in_month(CAL_GREGORIAN, $month,$year1);
$Total=$length  x 24  x $numberofday ;

cal_days_in_month()接受月份字段的整数值，请将月份转换为integer:

$month = "april";
$year1 = "2013";
$month = date('m', strtotime($month));

在使用函数之前。

$numberofday = cal_days_in_month(CAL_GREGORIAN, $month, $year1);

cal_days_in_month:的替代方案

$month = "april";
$year1 = "2013";
$numberofday = date('t', strtotime("$year1-" . date("m",strtotime($month)) . "-01"));

还有：

$Total=$length  x 24  x $numberofday;

应该是：

$Total=$length * 24 * $numberofday;

您有'length'，应该是$length吗？

$month=4；

$year1=2013；

$numberofday=cal_day_in_month（cal_GREGORIAN，$month，$year1）；

echo$numberofday//30