cal_days_in_month

Return the number of days in a month for a given year and calendar (PHP 4 >= 4.1.0, PHP 5)
int cal_days_in_month ( int calendar, int month, int year )

This function will return the number of days in the month of year for the specified calendar.

例 338. cal_days_in_month() example

<?php
$num
= cal_days_in_month(CAL_GREGORIAN, 8, 2003); // 31
echo "There was $num days in August 2003";
?>

See also jdtounix().