Simple vending machine with one drink in python

Question

I’m nearly finishing this project but still get an error saying my code doesn’t accept invalid inputs, for example…if I input a string instead of an integer throws an error instead of accepting and show a message.

This is the error i get…

Any help would be really appreciated!

:( coke rejects invalid amount of cents
    Did not find "50" in "Amount Due: 20..."

the code:

def main():
    total = 0
    while True:
        total += int(input("Insert one coin at a time: ").strip())
        coke = 50
        print(total)
        if total > coke:
            print("Change Owed =", total - coke)
            return
        elif total == coke:
            print("No Change Owed, Here's a coke ")
            return
        else:
            print("Amount Due =", coke-total)


main()

Asked By: user17892586

||

Source

Answer 1

You have to remove any excess ' and " from your string input.
This can be done with the .replace method:

def main():
    total = 0
    while True:
        total += int(input("Insert one coin at a time: ").replace('"', '').replace("'", '').strip())
        coke = 50
        print(total)
        if total > coke:
            print("Change Owed =", total - coke)
            return
        elif total == coke:
            print("No Change Owed, Here's a coke ")
            return
        else:
            print("Amount Due =", coke-total)


main()

Answered By: Nin17

Answer 2

If you can’t fulfill the requirement because your code should accept invalid inputs, for example letters, and not crash, you could try the following with a try-expect-block

def main():
    total = 0
    while True:
        try:
            total += int(input("Insert one coin at a time: ").strip())
        except ValueError:
            print("The input is not a number, please only enter numbers")
        else:
            coke = 50
            print(total)
            if total > coke:
                print("Change Owed =", total - coke)
                return
            elif total == coke:
                print("No Change Owed, Here's a coke ")
                return
            else:
                print("Amount Due =", coke-total)


main()

For more information about using exception i would suggest you to read the Python-documentation

Answered By: Mime

Answer 3

when you say you input a string, do you mean like "20" with quotation marks?

if so put .replace(‘"’,”).replace("’","") next to .strip() will sort that out to get rid of " and ‘ .

total += int(input("Insert one coin at a time: ").strip().replace('"','').replace("'",""))

Answered By: tgm_learn

Answer 4

Try-Except would be a way out, but as we didn’t see it yet in cs50p week 2, i suspect we should find an answer without using it.
The thing your code is missing is a validation to check if the input is a 5, 10 or 25 cent coin. You can do that with:

if input in [5, 10, 25]:

Answered By: FelixOakz

Simple vending machine with one drink in python

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