此软件可以根据某年日月计算天数，反之也可以根据某年月日计算某天-This software can calculate a certain number of days of sun, moon, and vice versa can also be calculated based on one day a year, month day

给出从1年1月1日到某天的总天数，计算出年月日，并逆运算。-calculate date

判断输入的某年月日是当年的第几天，可用于益智类小游戏-Input to determine a date was the first few days, can be used to Puzzle game