Simple while loop in Python

Question

I am making a supermarket interface, and my program works fine if I run without going back. However, if userchoice = 2, I can't go back to userchoice = 1. I can only go to 2 or the options after it. I think there could be something wrong with my while loop.

apples = 0
mangoes = 0
print("Welcome to the CS110 Supermarket!")
print("1. Potatoes ($0.75 per potato")
print("2. Tomatoes ($1.25 per tomato")
print("3. Apples ($0.5 per apple")
print("4. Mangoes ($1.75 per mango")
print("5. Checkout")
user_choice = int(input())
total = total + potatoes*0.75 + tomatoes*1.25 + apples*0.5 + mangoes*1.75
while user_choice == 1:
    potatoes = int(input("How many potatoes?"))
    total = total + potatoes*0.75
    print("The total cost is $", total)
    print("Welcome to the CS110 Supermarket!")
    print("1. Potatoes ($0.75 per potato")
    print("2. Tomatoes ($1.25 per tomato")
    print("3. Apples ($0.5 per apple")
    print("4. Mangoes ($1.75 per mango")
    print("5. Checkout")
    user_choice = int(input())
while user_choice == 2:
    tomatoes = int(input("How many tomatoes?"))
    total = total + tomatoes*1.25
    print("The total cost is $", total)
    print("Welcome to the CS110 Supermarket!")
    print("1. Potatoes ($0.75 per potato")
    print("2. Tomatoes ($1.25 per tomato")
    print("3. Apples ($0.5 per apple")
    print("4. Mangoes ($1.75 per mango")
    print("5. Checkout")
    user_choice = int(input())
while user_choice == 3:
    apples=int(input("How many apples?"))
    total = total + apples*0.5
    print("The total cost is $", total)
    print("Welcome to the CS110 Supermarket!")
    print("1. Potatoes ($0.75 per potato")
    print("2. Tomatoes ($1.25 per tomato")
    print("3. Apples ($0.5 per apple")
    print("4. Mangoes ($1.75 per mango")
    print("5. Checkout")
    user_choice = int(input())
while user_choice == 4:
    mangoes = int(input("How many mangoes?"))
    total = total + mangoes*1.75
    print("The total cost is $",total)
    print("Welcome to the CS110 Supermarket!")
    print("1. Potatoes ($0.75 per potato")
    print("2. Tomatoes ($1.25 per tomato")
    print("3. Apples ($0.5 per apple")
    print("4. Mangoes ($1.75 per mango")
    print("5. Checkout")
    user_choice=int(input())
if user_choice == 5:
    print("The total cost is $",total)
    pay = float(input("Please enter an amount to pay for the fruits and vegetables: "))
    while pay < total:
        pay = float(input("Please enter an amount more than payment: "))
    change = pay - total
    print("Your change will be $", change)
    d5 = change // 5
    d1 = (change % 5) // 1
    quarter = ((change % 5) % 1) // 0.25
    dime = (((change % 5) % 1) % 0.25) // 0.1
    nickel = ((((change % 5) % 1) % 0.25) % 0.1) // 0.05
    penny = (((((change % 5) % 1) % 0.25) % 0.1) % 0.05) // 0.01
    print("Give the customer", d5, "$5 note,", d1, "$1 note,", quarter, "quarter,", dime, "dime,", nickel,"nickel,", penny, "penny.")

Try one while loop with an if for each of your options. — Fred Larson
– Fred Larson, Commented Dec 7, 2016 at 20:47

Will · Accepted Answer · 2016-12-07 20:49:46Z

2

You're using more whiles than you need. rather than a while for each option, use only one loop, and several ifs for options:

while True:
  user_choice=int(input())
  if user_choice == 1:
    ...
  if user_choice == 2:
    ...
  ...
  if user_choice == 5:
    break # exit the loop with break

answered Dec 7, 2016 at 20:49

Will

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User2342342351 · Accepted Answer · 2016-12-07 20:50:43Z

-1

You could use an infinite loop while putting the user_input at the top of the loop. Then, you just have to use if conditions. You are currently using one loop per parameter. This is not going to work since you can't get out that loop to process an other choice.

while True:
    print("Welcome to the CS110 Supermarket!")
    print("1. Potatoes ($0.75 per potato")
    print("2. Tomatoes ($1.25 per tomato")
    print("3. Apples ($0.5 per apple")
    print("4. Mangoes ($1.75 per mango")
    print("5. Checkout")

    user_choice = int(input())
    if user_choice==1:
        potatoes=int(input("How many potatoes?"))
        total=total+potatoes*0.75

    elif user_choice==2:
        tomatoes=int(input("How many tomatoes?"))
        total=total+tomatoes*1.25

    elif user_choice==3:
        apples=int(input("How many apples?"))
        total=total+apples*0.5


    elif  user_choice==4:
        mangoes=int(input("How many mangoes?"))
        total=total+mangoes*1.75


    if user_choice==5:
        print("The total cost is $",total)
        pay=float(input("please enter an amount to pay for the fruits and vegetables: "))
        while pay<total:
            pay=float(input("please enter an amount more than payment: "))
        change=pay-total
        print("your change will be $",change)
        d5 = change // 5
        d1 = (change % 5) // 1
        quarter = ((change % 5) % 1) // 0.25
        dime = (((change % 5) % 1) % 0.25) // 0.1
        nickel = ((((change % 5) % 1) % 0.25) % 0.1) // 0.05
        penny = (((((change % 5) % 1) % 0.25) % 0.1) % 0.05) // 0.01
        print("Give the customer", d5, "$5 note,", d1, "$1 note,", quarter, "quarter,", dime, "dime,", nickel,"nickel,", penny, "penny.")
        break

edited Dec 7, 2016 at 20:50

answered Dec 7, 2016 at 20:47

User2342342351

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2 Comments

MooingRawr Over a year ago

also instead of just code dumpping maybe explain yourself on what you did, and what OP did wrong ?

jjjdada Over a year ago

Thank you! This helps a lot !

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