How would I use input validation within a counter while loop in python code?

Question

Problem: Write a program that will allow a grocery store to keep track of the total number of bottles collected for recycling for seven days. The program should allow the user to enter the number of bottles returned for each of the seven days. The program will calculate the total number of bottles returned for the week and the amount paid out (the total returned times 10 cents.) The output of the program should include the total number of bottles returned and the total paid out.

My problem is that I need to add input validation within a counter while loop. For ex: if the user enters a number less than 0, my code needs to writes "Input cannot be less than 0" and then it will continue with the code. How can I do this?

This is my code:

totalBottles = 0

todayBottles = 0

totalPayout = 0

counter = 1

eachBottle = float(.10)

while counter <= 7:

    print ('Enter the number of bottles for today: ')

    todayBottles = int(input())

    totalBottles = totalBottles + todayBottles

    counter = counter + 1

    totalPayout = eachBottle * totalBottles

print ('The amount of bottles collected for the week are', totalBottles)

print ('The payout total for the week is $', totalPayout)

I've tried many things, such as modifying my code to make it loop like this, but it didn't work. I'm not sure how to structure an input validation. Please help.

totalBottles = 0

todayBottles = 0

totalPayout = 0

counter = 1

eachBottle = float(.10)

def main():

    answer = 'yes'

    while answer == 'yes' or answer == 'Yes':

        calculate_total()

        answer = input('Do you want to enter next week? (enter "yes" or "no" directly as displayed): ')

    print_statements()
    
def calculate_total():

    todayBottles = int(input('Enter todays bottles'))

    while todayBottles < 0:

        print ('ERROR: the amount cannot be nagative. ')

        while counter <= 7:

            todayBottles = int(input('Enter todays bottles '))

            totalBottles = totalBottles + todayBottles

            counter = counter + 1

            totalPayout = eachBottle * totalBottles

def print_statements():

    print ('The amount of bottles collected for the week are', totalBottles)

    print ('The payout total for the week is $', totalPayout)

You can just add a verification: `if todayBottles < 0: print('Input cannot be less than 0') continue`. This will avoid running the rest of your code if the input is < 0 and will repeat the while without incrementing the counter variable. — Alex Rintt, Nov 14 '22 at 22:16
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) — 0x5453, Nov 14 '22 at 22:19

score 1 · Answer 1 · answered Nov 14 '22 at 22:19

if the user enters a number less than 0, my code needs to writs "Input cannot be less than 0" and then it will continue with the code. How can I do this?

You can just add a verification and use the continue statement:

while counter <= 7:

    print ('Enter the number of bottles for today: ')

    todayBottles = int(input())

    if todayBottles < 0:
        print('Value not allowed, must be >= 0')
        continue

    totalBottles = totalBottles + todayBottles

    counter = counter + 1

    totalPayout = eachBottle * totalBottles

How would I use input validation within a counter while loop in python code?

1 Answers1