计算是这年的的第几天（判断闰年）能判断月份是否输入错误,如果是闰年还能计算2月份的日期输入是否过界!算法还算不错!-calculation is that the days of (determining a leap year) in the ability to determine whether an input error, If it is a leap year in February can calculate the date and whether community inpu