Question

UPDATED:

This Code Works:

# North Carolina Sales Tax Estimator
# Estimates the Amount of Tax You Should Pay in North Carolina

# Defines the Current 2012 Tax Rate
nctaxrate = 0.07

# Defines the tax variable by multipling subtotal by the current nc tax rate
# tax = subtotal * nctaxrate

# Defines the total variable by adding the tax variable to the subtotal variable
# total = subtotal + tax

# Defines the Subtotal from an Input of the User's Purchase Amount
def main():
    print("\t\t\tThis is the NC Sales Tax Estimator")
    print("\t\t Input Your Total Purchases Below\n")

    while True:
        subtotal = float(input("Enter the total price of your purchases:\t$").strip())
        if subtotal == -1: break
        tax = subtotal * nctaxrate
        total = subtotal + tax

        print("\tSUBTOTAL: $", subtotal)
        print("\t     TAX: $", tax)
        print("\t   TOTAL: $", total)

# if this script is called directly by Python, run the main() function
# (if it is loaded as a module by another Python script, don't)
if __name__=="__main__":
    main()

Here is the Original Question:

So I am learning Python and asked a previous question yesterday and was supplied with an awesome set of code that I decided to modify to work with an NC Sales Tax Estimator Program I wanted to create.

The one thing is that I am getting a break out loop error that I don’t quite understand. I’ve searched and tried to understand the meaning but I know the code worked before. Also the tax code program I created from scratch 🙂 worked before trying to add the fancy ability to submit many inputs in a loop until the user wanted to ‘exit’.

Here is the Code:

# North Carolina Sales Tax Estimator
# Estimates the Amount of Tax You Should Pay in North Carolina

# Defines the Current 2012 Tax Rate
nctaxrate = 0.07

# Defines the tax variable by multipling subtotal by the current nc tax rate
tax = subtotal * nctaxrate

# Defines the total variable by adding the tax variable to the subtotal variable
total = subtotal + tax

# Defines the Subtotal from an Input of the User's Purchase Amount
def main():
    print("\t\t\tThis is the NC Sales Tax Estimator")
    print("\t\t Input Your Total Purchases Below")

while True:
    subtotal = float(input("Enter the total price of your purchases (or 'exit' to quit) :\$").strip())
    if subtotal.lower()=='exit':
        break

    try:
        subtotal = int(subtotal)
    except ValueError:
        print("That wasn't a number!")

    try:
        print("\tSUBTOTAL: $", subtotal)
        print("\t     TAX: $", tax)
        print("\t   TOTAL: $", total)
    except KeyError:
        print("")

# if this script is called directly by Python, run the main() function
# (if it is loaded as a module by another Python script, don't)
if __name__=="__main__":
    main()

P.S. I only added the KeyError because I researched that you must have an error statement after a try. I’m just a beginner so I’m attempting to create programs myself and reading “Python for the Absolute Beginner”.

UPDATE:

I fixed the indentation but now I get the following traceback error:

Traceback (most recent call last):
  File "C:/LearningPython/taxestimator.py", line 30, in <module>
    tax = subtotal * nctaxrate
NameError: name 'subtotal' is not defined

I thought I defined it in the input ie.

subtotal = float(input("Enter the total price of your purchases (or 'exit' to quit) :\$").strip())

Is it because the other defines (tax and total) that use the defined subtotal are defined before subtotal is defined? I tried moving them below the defined subtotal but it didn’t work still.

Thanks for any Advice.

Best,

Steven

Answer 1

The main issue that you have is that Python requires whitespace to scope methods. Without that, then statements will run not as intended – for example:

while True:
    subtotal = float(input("Enter the total price of your purchases (or 'exit' to quit) :\$").strip())
if subtotal.lower()=='exit':
    break

will not break out of the loop with valid input (it will if you put a string there, but that’s another matter). Also, if everything is to be in the scope of main(), every statement requires one level of indentation (or four lines of whitespace, if you prefer). As it stands, your while won’t run in the scope of main().

Also, you make reference to subtotal before you actually give it a value. Since subtotalwasn’t properly initialized, you won’t have a value to use for it.

You would want to rewrite your code such that tax and total are defined after you define subtotal.

while True:
    subtotal = float(input("Enter the total price of your purchases (or 'exit' to quit) :\$").strip())
    if subtotal.lower()=='exit':
        break
    tax = subtotal * nctaxrate
    total = subtotal + tax

Finally, if subtotal, total, and tax are properly defined (which, after the above, they will be), there will be no need for the superflous try...except statement when you wish to print the values out.