Valueerror: Invalid Literal For Int() With Base 10: '1000.00'

I currently implementing a class called BankAccount. It offers the ability to set a balance, make a deposit, make a withdrawal, and check the balance. Now I have to write a functio

Solution 1:

The general approach is correct, but int is clearly wrong since apparently the amounts are expressed in "dollars.cents".

float would appear to work but would probably not be the right choice: handling monetary amounts is instead the primary reason the decimal module was added to the Python standard library! With decimal you'll get precise computations, without the risk of rounding errors losing or gaining a cent here and there which would unchain The Auditors upon you.

So here's how I'd do it...:

import decimal

classBankAccount:

    defset(self,balance=decimal.Decimal('0.00'):
        self.balance = balance  

# the rest of the class is fine.  Shd probably have an __init__ tho.# also should keep an audit trail of deposit and withdrawals!def processAccounts(fname):
    withopen(fname,'r') as f:
        start_bal = decimal.Decimal(next(f).strip())
        ba = BankAccount()
        ba.set(start_bal)
        for line in f:
            fields = line.strip().split()
            if fields:
                if fields[0] in'Ww':
                    ba.withdraw(decimal.Decimal(fields[1])
                elif fields[0] in'Dd':
                    ba.deposit(decimal.Decimal(fields[1])
                else:
                    print('Ignoring line: {!r}'.format(line.strip()))
    return ba

Solution 2:

First, since you are working with money the correct answer is to use the decimal class as suggested by Alex Martelli.

Having said that, the answer to the specific problem of the ValueError can be solved with a 3rd party module called fastnumbers (I am the author). It provides a function called fast_forceint that will corerce strings of floats to (i.e. '1000.00') to an int.

>>>from fastnumbers import fast_forceint>>>fast_forceint('1000.00')
1000
>>>isinstance(fast_forceint('1000.00'), int)
True

This library was specifically designed to ease the pain of converting strings to numeric types.

Solution 3:

To do so without using the decimal class (less accurate when working with floats), also including a constructor:

classBankAccount():

def__init__(self, initialBalance = 0):
    self.accBalance = initialBalance 

def__repr__(self):
    return("BankAccount({})".format(self.accBalance))

defset(self, amount):
    self.accBalance = amount

defdeposit(self, amount):
    self.accBalance += amount

defwithdraw(self, amount):
    self.accBalance -= amount

defbalance(self):
    return(self.accBalance)


defprocessAccount(filename ):
    withopen(filename,'r') as f:
        b = BankAccount()
        startBal = f.readline().split()
        startBal = float(startBal[0])
        b.set(startBal)

        for line in f:
            fields = line.strip().split()
            if fields[0] in'Ww':
            b.withdraw(float(fields[1]))
            elif fields[0] in'Dd':
                b.deposit(float(fields[1]))

    return b