Chapter 7, Problem 18PE

Program Plan Intro

Validation of date input

Program plan:

• Define the “leap_Year()” function,
  • Check whether the year is not divisible by "4",
    • If the condition is “True”, return “False”.
    • Otherwise, check whether the year is divisible by "100",
      • If it is “True”, check whether the year is divisible by "400",
        • If it is “True”, return “True”.
        • Otherwise, return “False”.
      • Otherwise, return “True”.
• Define the “main()” function,
  • Execute the “try” statement to raise the exception if it is occurred.
    • Get the input from the user.
    • Split the user input based on "/" using “split()”.
    • Convert the string type inputs into integer type.
    • Check whether either the month is greater than “12” or day is greater than “12”,
      • If it is “True”, print the string “This date is invalid”
      • Otherwise, check whether the day is less than or equal to “28”,
        • If it is “True”, print the string as “This date is valid”.
        • Otherwise, check whether the month is "2" and "29",
        • • If it is “True”, check whether the Boolean value return from “leap_Year()” is “False”.
            • If it is “True”, print “This date is invalid”.
            • Otherwise, print “This date is valid”.
          • Otherwise, check whether the day is “31”,
            • If it “True”, check whether the month is either "2" or "4" or "6" or "11",
            • If the above condition is “True”, print invalid.
            • Otherwise, print valid.
          • Otherwise, print “This date is valid”.
        • Catch the exception using “except ValueError” statement, if the exception of type “ValueError” occurs.
      • Handle the exception.
    • Catch the exception using “except” statement, if any type of exception occurs.
  • Call the function “main()”.

Program Description Answer

This Python program is to add decisions and exception handling as required making it truly robust.

Explanation of Solution

Program:

File name: “year.py”

#Define the function

def leap_Year(yr):

    #Check whether the year is not divisible by "4"

    if (yr % 4) != 0:

        #Return the boolean value

        return False

    #Otherwise

    else:

        #Check whether the year is divisible by "100"

        if (yr % 100) == 0:

            #Check whether the year is divisible by "400"

            if (yr % 400) ==0:

                #Return boolean value

                return True

            #Otherwise

            else:

                #Return boolean value

                return False

        #Otherwise

        else:

            #Return boolean value

            return True

#Define the function

def main():

    #Make a try

    try:

        #Get the input from the user

        date_Str = input("Enter a date in the form MM/DD/YYYY: ")

        #Split the user input based on "/" using split()

        month_Str, day_Str, year_Str = date_Str.split("/")

        #Convert the string into integer

        mon = int(month_Str)

        #Convert the string into integer

        d = int(day_Str)

        #Convert the string into integer

        yr = int(year_Str)

        #Execute the condition

        if mon > 12 or d > 31:

            #Print the string

            print("This date is invalid.")

        #Otherwise

        else:

            #Check whether the day is less than or equal to 28

            if d <= 28:

                #Print the string

                print("This date is valid.")

            #Check whether the month is "2" and "29"

            elif mon == 2 and d == 29:

                #Check whether the boolean value return from "leap_Year()" is "False"

                if leap_Year(yr) == False:

                    #Print the string

                    print("This date is invalid.")

                #Otherwise

                else:

                    #Print the string

                    print("This date is valid.")

            #Check whether the day is "31"

            elif d == 31:

                '''Check whether the month is either "2" or "4" or "6" or "11"'''

                if mon == 2 or 4 or 6 or 11:

                    #Print the string

                    print("This date is invalid")

                #Otherwise

                else:

                    #Print the string

                    print("This date is valid")

            #Otherwise

            else:

                #Print the string

                print("The date is valid.")

    #Catch the exception

    except ValueError:

        #Handle the exception

        print("Your input was not in the correct form.")

    #Catch the exception

    except:

        #Handle the exception

        print("Something went wrong!")

#Call the function

main()

Sample Output

Output:

Enter a date in the form MM/DD/YYYY: 02/30/2000

The date is valid.

>>>

Additional output:

Enter a date in the form MM/DD/YYYY: 02-05-2000

Your input was not in the correct form.

>>>

Additional output:

Enter a date in the form MM/DD/YYYY: 06/31/2000

This date is invalid

>>>