计算上一个月的今天

<?php$time = strtotime("2011-03-31");/** * 计算上一个月的今天，如果上个月没有今天，则返回上一个月的最后一天 * @param type $time * @return type */ function last_month_today($time){ $last_month_time = mktime(date("G", $time), date("i", $time), date("s", $time), date("n", $time), 0, date("Y", $time)); $last_month_t = date("t", $last_month_time); //二月份的天数 if ($last_month_t < date("j", $time)) { return date("Y-m-t H:i:s", $last_month_time); } return date(date("Y-m", $last_month_time) . "-d", $time);}echo last_month_today($time);var_dump(date("H",time()).date("a",time()));var_dump(date("Y-m-d H:i:s ",mktime(0,0,0,4,-31,2011)));?>