Question

Write a program, to accept a date as day, month & year from user and raise appropriate error(s), if legal value(s) is not supplied. Display appropriate message till user inputs correct value(s).

Answer 1

The program uses ValueError for non-numeric input and for dates that do not exist, such as 31 February.

from datetime import date

while True:
    try:
        day = int(input("Enter day: "))
        month = int(input("Enter month: "))
        year = int(input("Enter year: "))

        if year < 1:
            raise ValueError("Year must be positive.")

        valid_date = date(year, month, day)
        print("Valid date:", valid_date.strftime("%d-%m-%Y"))
        break

    except ValueError as error:
        print("Invalid date:", error)
        print("Please enter the date again.\n")

datetime.date() automatically checks the number of days in each month and leap-year rules.