Python小项目：实现日历功能

Python小项目：实现日历功能
功能：（1）输入年月日，输出这一天是星期几
（2）输入年份，打印该年日历

months=[0,31,28,31,30,31,30,31,31,30,31,30,31]
#判断任何一年的日历
def isLeap(y):
    return y%400==0 or y%4==0 and y%100!=0
#计算历史上某一天是星期几
#先计算是该年第几天
def countDays(y,m,d):
    global months
    days=d
    if isLeap(y):
        months[2]=29
    else:
        months[2]=28
    for n in range(1,m):
        days+=months[n]
    return days
#由历法公式计算第days天是星期几
def countWeek(y,m,d):
    days=countDays(y,m,d)
    y=y-1
    w=y+y//4+y//400-y//100+days
    w=w%7
    return w
#print(isLeap(2000))
#print(countWeek(2019,11,14))
def printWeek():
    global months
    s=input('yyyy-mm-dd:')
    s=s.split('-')
    if len(s)==3:
        try:
            y=int(s[0])
            m=int(s[1])
            d=int(s[2])
            if y<0:
                raise Exception('无效的年份')
            if m<0 or m>12:
                raise Exception('无效的月份')
            if isLeap(y):
                months[2]=29
            else:
                months[2]=28
            if d<1 or d>months[m]:
                raise Exception('无效的日期')
            w=countWeek(y,m,d)
            week=['日','一','二','三','四','五','六']
            print(y,m,d,'星期'+week[w])
        except Exception as e:
            print(e)
    else:
        print('无效的日期')
#         
def printMonth(y,m):
    global months
    w=countWeek(y,m,1)
    if isLeap(y):
                months[2]=29
    else:
                months[2]=28
    md=months[m]
    print('%-6s%-6s%-6s%-6s%-6s%-6s%-6s'%('Sun','Mon','Tue','Wed','Thu','Fri','Sat'))
    for i in range(w):
        print('%-6s'%'',end='')
    for d in range(1,md+1):
        print('%-6d'%d,end='')
        w+=1
        if w%7==0:
            print()
#打印年份           
def printCalandar():
    try:
        y=input('输入年份：')
        y=int(y)
        for m in range(1,13):
            print()
            print('-----------',y,'年',m,'月 -----------')
            printMonth(y,m)
            print()
    except Exception as e:
        print(e)
      
while True:
    print()
    print('1.计算某天星期几')
    print('2.打印某年的日历')
    print('3.退出')
    s=input('请选择（1，2，3）')
    if s=='1':
        printWeek()
    elif s=='2':
        printCalandar()
    elif s=='3':
        break