How to make a loop that validates the user-input dates based on the functions created?-CodePudding

I am not using any datetime module. I created my own functions to calculate the day, month, and year. I want to calculate the refunds based on the date. If the date is invalid, it should ask the user to try again until a date is true.

year = 0
month = 0
day = 0
money_owed = 0

def if_leap_year(year):

    if (year % 400 == 0): return 366
    
    elif (year % 100 == 0): return 365
    
    elif (year % 4 == 0): return 366

    else:
        return 365

#print(if_leap_year(year))

def days_in_month(month, year):
    if month in {1, 3, 5, 7, 8, 10, 12}:
        return 31
    if month == 2:
        if if_leap_year(year):
            return 29
        return 28
    return 30

#print(days_in_month(month, year))

def is_valid_date(year, month, day):
  if days_in_month(month, year)<day:#checks if the given day is possible 
given the month
    return False
  else:
    return True



def days_left_in_year(month, day, year):
    daysInMonth = [31,28,31,30,31,30,31,31,30,31,30,31]
    daysLeft = (if_leap_year(year) if month < 3 else 365) - 
sum(daysInMonth[:month - 1]) - day
    return daysLeft

def refund_period():
        month = int(input("Enter the month of the year: "))
        day = int(input("Enter the day of the year: "))
        year = int(input("Enter the year to determine the number of days: "))      
        if is_valid_date(year , month , day):
            money_owed = (days_left_in_year(month, day, year) / 
if_leap_year(year)) * 278
            return round(money_owed, 2)
        else:
            print("Your date is invalid, try again.")


while is_valid_date(year, month, day):
    print('you will be refunded','$',   refund_period())
    break
else:
    print("Your date is invalid, try again.")

I am getting:

you will be refunded $ -8.38

even though the calculation shouldn't be performed since the date is invalid

CodePudding user response：

Your while loop is not comparing the function value but just checking if the object exists. Instead of conditions like while days_left_in_year(month, day, year), use conditions like while days_left_in_year(month, day, year)<30 (assuming you wanted to deny refunds on orders older than 30 days.

To validate dates, add the following function under your comment #print(days_in_month(month, year)):

def is_valid_date(year, month, day)
  if days_in_month(month, year)<day:#checks if the given day is possible given the month
    return False
  else:
    return True

then your condition should look something like this:

if is_valid_date(year, month, day) == True:
    print('you will be refunded','$',   refund_period())
else:
    print("Your date is invalid, try again.")

CodePudding user response：

You are setting year =0 , month =0, day = 0 in first loop. Also the while is not clear. All your functions return an int so never validate if the date is correct. Maybe you can create a function to validate the date something like this :

def is_valid_date(year , month , day):
    ##logic to validate

and you can change this function :

    def refund_period():
        month = int(input("Enter the month of the year: "))
        day = int(input("Enter the day of the year: "))
        year = int(input("Enter the year to determine the number of days: "))      
        if is_valid_date(year , month , day):
            money_owed = (days_left_in_year(month, day, year) / if_leap_year(year)) * 278
            return round(money_owed, 2)
        else :
            print("Your date is invalid, try again.")

Just a couple of comments:

You are getting the year, month, and day using input() so you don't need to create global variables for that.
you don't need to ask if if_leap_year(year) == 365 or 366 because this function returns 365 or 366 so you can use it directly when you calculate the money_owned, as I do.