Not very user friendly message for non-INT number Exception

Hi Niusha!

This is probably overkill, but I hope it can answer your question.

First, go here (and look at point/example 3. "Handling multiple exceptions with one except block"):

https://www.techbeamers.com/use-try-except-python/

One thing about inputs is that they return string values only.

So if a user inputs 123, the value stored in the variable will actually be '123' (a number string) and not 123

So you can't test for (not being a number value) using something like this:

res = isinstance(test_string, str)

becaue ANY response from an input would evaluate to TRUE.

So notice my reverse-logic work-around to do a workable test for number-ness.

(And make sure your indents are precisely 4/8/12/16/20/etc... spaces only - don't use tabs.)

Here is a version of my solution (which goes beyond the challenge) with error handling:

TICKET_PRICE = 10

tickets_remaining = 100  

while tickets_remaining >= 1:
    if tickets_remaining > 1:
        verb = "are"
        remaining_s = "s"
    else:
        verb = "is"
        remaining_s = ""
    print("There {} {} ticket{} remaning (at $10.00 per ticket).".format(verb, tickets_remaining, remaining_s))
    valid = False
    while valid != True:
        client_name = input("What is your name? ")
        if (len(client_name) == 0):
            print("*** INVALID SELECTION ***")
        else:
            try:
                val = int(client_name) ###  IF THIS FAILS, client_name is a string - the desired value type  ###
            except ValueError: ###  BACKWORDS LOGIC HERE  ###
                valid = True ### Only valid on the exception!?! ###
            else:
                print("*** INVALID SELECTION ***")
    valid = False
    while valid != True:
        num_ticket = input("{}, how many tickets do you want to purchase? ".format(client_name))
        try:
            val = int(num_ticket)
        except ValueError:
            print("*** INVALID SELECTION ***")
            continue
        if val <= tickets_remaining:
            valid = True
        else:
            print("*** ERROR ***: There {} only {} ticket{} remaining. Try again.".format(verb, tickets_remaining, remaining_s))
    num_ticket = int(num_ticket)
    if num_ticket > 1:
        num_s = "s"
    else:
        num_s = ""
    amount_due = num_ticket * TICKET_PRICE
    print("The total amout due is ${}.00 for {} ticket{}.".format(amount_due, num_ticket, num_s))
    user_info = input("Do you want to procced Y/N? ").lower()
    if user_info == "y":
        print("SOLD!!!")
        tickets_remaining -= num_ticket
    else :
        print("Thanks anyways, {}".format(client_name))
print("Tickets soldout! :( ")

If you notice, in one section (the first try/except/else block) I sort of use ValueError backwards, but it makes it work. - I try to cast clientName to an int, and when it errors, I know it's a string (and therefore valid when it errors!?!) Again, kind of backwards logic, but sometimes you have to think outside-the-box!?! LOL

I had to do a lot of research and testing to figure that out.

Notice also that although I could have used raise ValueError in places, but opted not to and it still has workable/correct logic.

From this thread:

https://teamtreehouse.com/community/can-someone-help-me-with-this-python-script

You can test it here:

https://www.katacoda.com/courses/python/playground (run it with python3 app.py)

I hope this all helps.

Stay safe and happy coding!

Hi Peter,

Thanks for your answer, I really enjoyed your outside the box backward logic after I could figure it out (I'm a beginner in Python). Your reply answered a couple of other questions I had but since I deemed them to be minor I was delaying asking them for now(e.g. how to make sure the user input name is actually valid). But my question was simpler :) and I realize I may not have worded it accurately. I wanted to know why Craig in the video chose to handle both exceptions with one except block. Because he uses {} in his error message to the user, when the message is for a non-INT input, it is not very user friendly. He could've raised an "Exception" and then handle it in a separate block so he could have a more user friendly error message.

These might help:

https://www.journaldev.com/23417/python-catch-multiple-exceptions

https://www.programiz.com/python-programming/exception-handling

https://code.tutsplus.com/tutorials/how-to-handle-exceptions-in-python--cms-28621

I hope they help.

Stay safe and happy coding!