python while循环不退出

Question

我正在编写一个简单的程序，但我无法摆脱这个循环。我想要做的是，如果提款金额大于您的余额，请转到 while 循环。 while 循环应该得到一个新的输入并检查新的输入是否大于余额，如果是重复的，如果不是则转到 else，这是我打印余额的地方

class Account(object):
balance = 0
accountNumber = 0

def __init__(self, f, l, ssn, b):
    self.firstName = f
    self.lastName = l
    self.socialSecurity = ssn
    self.balance = b
    self.accountNumber = randint(0, 10000)

def __str__(self):
    return self.firstName + " " + self.lastName + \
           "'s balance is $" + str(self.balance) + \
           ". Your account Number is " + str(self.accountNumber)

def deposit(self, amount):
    depositAmount = amount
    balance = self.balance + depositAmount

    print(str(depositAmount) + " has been deposited into account "
                               "#" + str(
        self.accountNumber) + " Your balance is "
                              "now " + str(balance))
    return self.balance

def withdraw(self, amount):
    withdrawAmount = amount
    balance = self.balance - withdrawAmount
    if float(withdrawAmount) > float(balance):
        while float(withdrawAmount) > float(balance):
            print("Insufficient Funds, Enter new amount")
            withdrawAmount = raw_input(">")
    else:
       print(str(withdrawAmount) + " has been taken out of account "
                                "#" + str(
        self.accountNumber) + " Your balance is "
                              "now " + str(balance))



testOne = Account("John", "Smith", "1111", 1000)
print(testOne)
print(testOne.accountNumber)
testOne.deposit(200)
testOne.withdraw(5000)

我的问题是无论我说什么我都卡在 while 循环中输入新金额

Answer 1

raw_input() returns 一个字符串。您需要将其转换为 float 或 int，例如：

withdrawAmount = float(raw_input(">"))

Answer 2

试试这个：

if withdrawAmount > balance:
    while withdrawAmount > balance:
        print "Insufficient Funds, Enter new amount"
        withdrawAmount = int(raw_input())

这给了我这个（余额 = 50）：

...
Try again
60
Try again
30
>>>

您不需要 else 语句，因为代码会在退出 while 循环后退出块。

Answer 3

柯克是对的。

raw_input() 生成字符串，而不是数值。我怀疑 balance 也是使用 raw_input() 创建的，是吗？如果是这样，那么您是在将字符串与字符串进行比较，而您认为您是在比较数字。这就是你陷入这个循环的原因。确保您具有预期类型的比较变量。

试试这个：

if float(withdrawAmount) > float(balance):
        while float(withdrawAmount) > float(balance):
            print("Insufficient Funds, Enter new amount")
            withdrawAmount = raw_input(">")
else:
    print

如果这可行，我的假设可能是正确的。

但我建议在这个片段之前检查您的代码以确保 balance 实际上是 int 或 float，并将 withdrawAmount 设置为 float（或int）在输入处输入（正如柯克建议的那样）；这样你就可以比较数字并且一切正常。

编辑：

好的，我发现你的代码有问题。实际上，在比较它们之前，您从余额 中减去 withdrawAmount。试试这个：

def withdraw(self, amount): withdrawAmount = amount balance = self.balance while withdrawAmount > balance: print("Insufficient Funds, Enter new amount") withdrawAmount = int(raw_input(">")) balance = balance - withdrawAmount print(...)

Answer 4

这是一种方法：

balance = 100
withdrawAmount = float(raw_input(">"))
while withdrawAmount > balance:
    withdrawAmount = float(raw_input("Insufficient Funds, Enter new amount: "))
print "Thank You"

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