How can I handle 2 errors from user input in a while true loop

Question

I am trying to make sure that the user enters only "s/r/e" in the shipping method input. The program is not handling the errors correctly for shipping method input. I am able to handle the input errors for the number of items. I am wondering if I am able to handle multiple errors under a single while true block. Any other recommended solutions are greatly appreciated! This is what I have tried to do:

def mail_price_calculator(items, shipping_method):
    if items <= 50:

        cost = 3
        if shipping_method == "s":
            postage = 10
            ship_by = "Standard post:"
        elif shipping_method == "r":
            postage = 15
            ship_by = "Registered post:"

        elif shipping_method == "e":
            postage = 20
            ship_by = "Express post:"

    if items > 50:

        cost = 2
        if shipping_method == "s":
            postage = 0
            ship_by = "Standard post:"
        elif shipping_method == "r":
            postage = 10
            ship_by = "Registered post:"
        elif shipping_method == "e":
            postage = 17
            ship_by = "Express post:"

    item_cost = items * cost
    calculation = (items * cost) + postage
    print("Receipt: ")
    print(f"{items} items x ${cost} = ${item_cost}")
    print(f"{ship_by} ${postage}")
    print(f"Total: ${calculation}")

    return calculation


while True:
    try:
        items = int(input("Enter the number of items: "))
    except ValueError:
        print("Sorry, please enter a number\n")
        continue
    if items == 0:
        print("Sorry, number of item cannot be 0\n")
    else:
        break
while True:
    try:
        shipping_method = str(input("Enter shipping method (s/r/e): "))
    except ValueError:
        print("Please enter an alphabet: \n")
        continue
    if shipping_method != ("s", "r", "e", "S", "R", "E"):
        print("Sorry, please enter a valid shipping method (s/r/e): \n")
    else:
        break
print()
mail_price_calculator(items, shipping_method)

Does this answer your question? [Asking the user for input until they give a valid response](https://stackoverflow.com/questions/23294658/asking-the-user-for-input-until-they-give-a-valid-response) — Pranav Hosangadi, Jul 08 '22 at 16:54

The Thonnu · Answer 1 · 2022-07-08T16:50:43.330

1

Replace this line:

if shipping_method != ("s", "r", "e", "S", "R", "E")

with:

if shipping_method not in ("s", "r", "e", "S", "R", "E")

Or even:

if shipping_method.lower() not in "sre"

P.S. the try/except while defining shipping_method is unnecessary - input always returns a string and raises no errors

edited Jul 08 '22 at 16:50

answered Jul 08 '22 at 16:42

The Thonnu

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2

even better `if shipment_method.lower() not in 'sre'` – user_na Jul 08 '22 at 16:46
`if shipping_method.lower() not in ("s", "r", "e")` looks pretty good – QwertYou Jul 08 '22 at 16:46
@user_na, yes!! – QwertYou Jul 08 '22 at 16:46

How can I handle 2 errors from user input in a while true loop

1 Answers1