为什么This Day Counter会产生错误的结果？

问题1：

您的闰年计算已关闭：

闰年years % 4 == 0但仅限于年份，year % 100 == 0除非它们也是year % 400 == 0：

2004,2008,2012 : leap year (%4==0, not %100==0)
1700,1800,1900 : no leap year (%4 == 0 , % 100 == 0 but not %400 == 0)
1200,1600,2000 : leap years (* 1200 theor. b/c gregorian cal start)

问题2：

在您的输入中，您将年份乘以 365，不检查闰年 - 他们应该有 366 天，但得到 365 - 这将导致在计算闰年的天数时缺少天数（ed）。

问题 3：

你有一个控制流问题：get_second_day()重复，因为你这样做：

get_first_date()
    while without end:
        do smth
        call get_second_date(..)
             while without end:
                 do smth 
                 call some calculation functions
                     that calc and print and return with None 
                 back in get_second_date(), no break, so back to the beginning
                 of its while and start over forever - you are TRAPPED

• 通过break在convert_dates_and_months(date_1, date)里面放一个after 来修复它get_second_day(..)

建议：

您可以通过减少之间的重复代码的数量简化输入get_first_day()和get_second_day()-这遵循DRY原则（d on't [R EPEAT Ÿ我们自己）：

def getDate(text):
    while True:
        try:
            print(text)
            day = int(input('Day:'))
            month = int(input('Month:'))
            year = int(input('Year:'))
            print(day, '/', month, '/', year)
            return [day, month, year * 365]  # see Problem 2
        except ValueError:
            print('You were supposed to enter a date.')


def get_first_day():
    date1 = getDate("First Date")
    # rest of code omitted 

def get_second_day(date_1):
    date = getDate("Second Date")
    # rest of code omitted 

更好的解决方案是使用datetime 和 datettime-parsing，特别是如果您想处理输入验证和闰年估计，则需要进行更多检查。

使用datetime模块可以大大简化这一点：

import datetime

def getDate(text):
    while True:
        try:
            print(text)
            day = int(input('Day:'))
            month = int(input('Month:'))
            year = int(input('Year (4 digits):'))
            print(day, '/', month, '/', year)

            # this will throw error on invalid dates: 
            # f.e. 66.22.2871 or even (29.2.1977) and user
            # gets a new chance to input something valid
            return datetime.datetime.strptime("{}.{}.{}".format(year,month,day),"%Y.%m.%d")
        except (ValueError,EOFError):
            print('You were supposed to enter a valid date.')


def get_first_day():
    return getDate("First Date")

def get_second_day():
    return getDate("Second Date")

# while True: # uncomment and indent next lines to loop endlessly
first = get_first_day()     # getDate("First Date") and getDate("Second Date") 
second = get_second_day()   # directly would be fine IMHO, no function needed
print( (second-first).days) 

输出：

First Date
Day:10
Month:9
Year (4 digits):2003
10 / 9 / 2003
Second Date
Day:6
Month:6
Year (4 digits):2006
6 / 6 / 2006
1000 

好读物：如何调试小程序 (#1) - 遵循它，至少可以引导您解决控制流问题。