On executing the code, else clause in main function is not working

Question

I am trying to run this code

def main():
    month_name = [
         "January",
         "February",
         "March",
         "April",
         "May",
         "June",
         "July",
         "August",
         "September",
         "October",
         "November",
         "December"
         ]

    while True:
        try:
            date = dated(input("Date: "))
            month, day, year = date

            if int(day) <= 31:
                if 1<= int(month) <= 12:
                    month = month.zfill(2)
                    print(f"{year}-{month}-{day}")
                    break
                else:
                    if int(day) <= 31:
                        for i in range(len(month_name)):
                            if month_name[i] == month:
                                month = i+1
                                month = month.zfill(2)
                                print(f"{year}-{month}-{day}")
                                break
                            else:
                                return ValueError
        except ValueError:
            continue

def dated(s):
      if "/" in s:
        s = s.split("/")
        if len(s[1]) == 1:
            s[1] = s[1].zfill(2)
            return s
        else:
            return s

      else:
        s = s.split(" ")
        s[1] = s[1].replace(",","")
        if len(s[1])== 1:
            s[1] = s[1].zfill(2)
            return s
        else:
            return s





if __name__ == "__main__":
     main()

The purpose of this code is if an user provides input of date in mmddyyyy format specifically like 10/08/1991 or October 8, 1991 it will display the date in yyyymmdd format like 1991-10-08. On executing this code for date format 10/08/1991, if the input is in range it works otherwise also the loop breaks but if the input is in second format October 8, 1991 the code is not working on trying to debug I found that for

while True:
        try:
            date = dated(input("Date: "))
            month, day, year = date

            if int(day) <= 31:
                if 1<= int(month) <= 12:
                    month = month.zfill(2)
                    print(f"{year}-{month}-{day}")
                    break

the code is running fine but after that for

else:
                    if int(day) <= 31:
                        for i in range(len(month_name)):
                            if month_name[i] == month:
                                month = i+1
                                month = month.zfill(2)
                                print(f"{year}-{month}-{day}")
                                break
                            else:
                                return ValueError

the code is not working. if I input October 10, 1991 the code will jump straight to

except ValueError:
    continue

and I input 15/10/1991 the code breaks out. The problem is coming only in if else part of main function, dated function is working perfectly fine.

Answer 1

Here is a much cleaner way of achieving the same using the built-in datetime module.

from datetime import datetime

def convert_date_to_yyyymmdd(date_str):
    try:
        # Try to parse the date in mm/dd/yyyy format
        date_obj = datetime.strptime(date_str, '%m/%d/%Y')
    except ValueError:
        try:
            # Try to parse the date in Month dd, yyyy format
            date_obj = datetime.strptime(date_str, '%B %d, %Y')
        except ValueError:
            # If both formats fail, raise an error
            raise ValueError("The date format is not recognized. Please use mm/dd/yyyy or Month dd, yyyy format.")
    
    # Convert the datetime object to the desired string format
    return date_obj.strftime('%Y-%m-%d')

# Example usage:
date1 = "10/08/1991"
date2 = "October 8, 1991"

print(convert_date_to_yyyymmdd(date1))  # Output: 1991-10-08
print(convert_date_to_yyyymmdd(date2))  # Output: 1991-10-08

which returns:

1991-10-08
1991-10-08

Note that the datetime module has a multitude of other useful features too which will save you from reinventing the wheel.