Can't exit while-loop with “Enter” key; need only “Y” to enter me into while-loop

Question

# Create a class called "Loan":
# Data fields in the Loan class include: Annual Interest Rate(Float),\
# Number of years of loan(Float), Loan Amount(Float), and Borrower's Name(string)
class Loan:
    # Create the initializer or constructor for the class with the above data fields.
    # Make the data fields private. 
    def __init__(self, annualInterestRate, numberOfYears, loanAmount, borrowerName):
        self.__annualInterestRate=annualInterestRate
        self.__numberOfYears=numberOfYears
        self.__loanAmount=loanAmount
        self.__borrowerName=borrowerName
        self.monthlyPayment__ = None
        self.totalPayment__ = None
    # Create accessors (getter) for all the data fields: 
    def getannualInterestRate(self):
        return self.__annualInterestRate
    def getnumberOfYears(self):
        return self.__numberOfYears
    def getloanAmount(self):
        return self.__loanAmount
    def getborrowerName(self):
        return self.__borrowerName
    # Create mutators (setters) for all the data fields:
    def setannualInterestRate(self):
        self.__annualInterestRate=annualInterestRate
    def setnumberOfYears(self):
        self.__numberOfYears=numberOfYears
    def setloanAmount(self):
        self.__loanAmount=loanAmount
    def setloanAmount(self,loan2):
        self.__loanAmount=loan2
    def setborrowerName(self):
        self.borrowerName=borrowerName
    # Create a class method: getMonthlyPayment - 
    def getMonthlyPayment(self,loanAmount, monthlyInterestRate, numberOfYears):
        monthlyPayment = loanAmount * monthlyInterestRate / (1- \
        (1 / (1 + monthlyInterestRate) ** (numberOfYears * 12)))
        return monthlyPayment
    # Create a class method: getTotalPayment - 
    def getTotalPayment(self):
        monthlyPayment = self.getMonthlyPayment(float(self.getloanAmount()), 
        float(self.getannualInterestRate()) / 1200, 
        int(self.getnumberOfYears()))
        self.monthlyPayment__=monthlyPayment
        totalPayment =self.monthlyPayment__ * 12 \
        * int(self.getnumberOfYears())
        self.totalPayment__=totalPayment
        return self.totalPayment__

# Write a test program (main function) to allow the user to enter the following: 
def main():
    loan1=Loan(float(input(("Enter yearly interest rate, for exmaple, 7.25: "))),\
               float(input(("Enter number of years as an integer: "))),\
               float(input(("Enter loan amount, for example, 120000.95: "))),\
               input(("Enter a borrower's name: ")))
    print()
    print("The loan is for", loan1.getborrowerName())
    print("The monthly payment is", format(loan1.getMonthlyPayment(loan1.getloanAmount(), \
    (loan1.getannualInterestRate()/1200), loan1.getnumberOfYears()), '.2f'))
    print("The total payment is", format(loan1.getTotalPayment(), '.2f'))
    print()
    loan_change=print(input("Do you want to change the loan amount? Y for Yes OR Enter to Quit: "))
    while loan_change!="":
            print()
            loan2=float(input("Enter a new loan amount: "))
            loan1.setloanAmount(loan2)
            print("The loan is for", loan1.getborrowerName())
            print("The monthly payment is", format(loan1.getMonthlyPayment(loan1.getloanAmount(), \
            (loan1.getannualInterestRate()/1200), loan1.getnumberOfYears()), '.2f'))
            print("The total payment is", format(loan1.getTotalPayment(), '.2f'))
            print()
            loan_change=print(input("Do you want to change the loan amount? Y for Yes OR Enter to Quit: "))

main()

As it stands, when I enter any key I am taken inside the while-loop when it should be kicking me out . This is wrong. I would like it so that only "Y" can enter me into the while-loop and that when the "Enter" key is struck, the program is terminated into >>> .

How can I solve this?

I've done some research and was told to use the double quotation method to have the "Enter" key kick out of while-loop, but as you can see it is not working as it stands in my code.

Answer 1

You currently take the value of the print statement as the value of loan_change:

loan_change=print(input("Do you.."))

This is the main reason of the problem currently, you don't need a print statement there, as the value of the print function is None , so your while loop condition fails later, as None != "" will evaluate True always.

Instead, simply use this to get the value of loan_change :

loan_change = input("Do you..")

Note that the input function, if provided a string inside will automatically print it while asking, so the print is not needed at all:

>>> input("Enter some value: ")
Enter some value: 123
'123'

---

Also, You should change your while loop condition to

while loan_change == "Y":

This will ensure that you enter the loop only when you have an entered a Y, and any other string will exit/skip the loop.

Answer 2

On this line:

loan_change=print(input("Do you want to change the loan amount? Y for Yes OR Enter to Quit: "))

You print the return value of the input function. Then you assign the return value of print to loan_change . Since print doesn't return anything, loan_change will be of type NoneType .

Next, you check whether loan_change is not equal to "" . Since loan_change has a completely different type from "" , they will not be equal. The condition is satisfied, and the while loop executes.

To fix it, change your code to this:

loan_change=input("Do you want to change the loan amount? Y for Yes OR Enter to Quit: ")
while loan_change=="Y":
        print()
        loan2=float(input("Enter a new loan amount: "))
        loan1.setloanAmount(loan2)
        print("The loan is for", loan1.getborrowerName())
        print("The monthly payment is", format(loan1.getMonthlyPayment(loan1.getloanAmount(), \
        (loan1.getannualInterestRate()/1200), loan1.getnumberOfYears()), '.2f'))
        print("The total payment is", format(loan1.getTotalPayment(), '.2f'))
        print()
        loan_change=input("Do you want to change the loan amount? Y for Yes OR Enter to Quit: ")