Finding the date of the next day-python

I need to find the date of the next day but without the datetime module

For example, First I have a function that take a date in parameter and I need to validate the date format via a input if the date format is right I display the date of the next day if the day format is wrong I simply display a message "it's not the good date format"

 def tomorrow(date : str) -> str:
    
    
    format='AAAA-M-J'  
    
    if begin == 'YES':
        
        year = int(input('Chose a year:'))
        month = int(input('Chose a month:'))
        day = int(input('Chose a day:'))


        if month == 12 and day == 31:
            
            year = year=+1
            month = month=+1
            day = day=+1
            date = str(f'{year}-{month}-{day}')
            if len(date) == len(format):
                return print('next date:' + date)
            
        elif day == 30 and month%2 != 0 or day == 31 and month%2 == 0:
            
            month = month=+1
            day = day=+1
            date = str(f'{year}-{month}-{day}')
            if len(date) == len(format):
                return print('next date:' + date)
            
        elif day < 30 or 31:
            
            day = day=+1
            date = str(f'{year}-{month}-{day}')
            if len(date) == len(format):
                return print('next date:' + date)
        else:
            return print('Not a good date format')
                    
            
    else:
        return print('NO')
        

date = print('date')

begin = str(input('type YES or NO'))
  


print(tomorrow(date))

nothing is displayed at the end

What's wrong ?

Solution 1:

1. Your function doesn't seem to need the date parameter, it is reassigned inside the function
2. The print function returns None, so your function tomorrow will always return None.
3. year = year=+1 is equivalent to year = 1, you need to determine if this is what you want.
4. There is a problem with the way to determine whether the time string is in the correct format, such as len("2021-10-21") != len("AAAA-M-J").

The above is the existing problem, I have made the modification below.

Is the format of the time string using regular matching(re) correct, and simplify part of the code.

\d For Unicode (str) patterns: Matches any Unicode decimal digit (that is, any character in Unicode character category [Nd]). This includes [0-9], and also many other digit characters. If the ASCII flag is used only [0-9] is matched.

{m,n} Causes the resulting RE to match from m to n repetitions of the preceding RE, attempting to match as many repetitions as possible. For example, a{3,5} will match from 3 to 5 'a' characters. Omitting m specifies a lower bound of zero, and omitting n specifies an infinite upper bound. As an example, a{4,}b will match 'aaaab' or a thousand 'a' characters followed by a 'b', but not 'aaab'. The comma may not be omitted or the modifier would be confused with the previously described form.

\d{4}-\d{1,2}-\d{1,2}

This regular expression means a string that matches four numbers and one or two numbers one or two numbers, and is concatenated using -. For example: 2021-1-1, 2021-12-29.

import re

date_rule = re.compile(r"\d{4}-\d{1,2}-\d{1,2}")


def tomorrow(begin) -> str:
    if begin == 'YES':

        year = int(input('Chose a year:'))
        month = int(input('Chose a month:'))
        day = int(input('Chose a day:'))

        # Determine if it is the last day of the year.
        if month == 12 and day == 31:
            year += 1
            month = 1
            day = 1

        # Determine if it is the last day of the month.
        elif day == 30 and month % 2 != 0 or day == 31 and month % 2 == 0:
            month += 1
            day = 1

        # In other cases, that is, it is not the last day of the year or month, the number of days is incremented by 1.
        else:
            day += 1

        date = f'{year}-{month}-{day}'
        # If it can match successfully, it means that the format is correct.
        if date_rule.match(date):
            return 'next date:' + date
        else:
            return 'Not a good date format'

    else:
        return 'NO'


print('date')
begin = input('type YES or NO')

print(tomorrow(begin))