python - 计算 for 循环期间的运行总计 - Python

Question

编辑:下面是我根据收到的反馈/答案编写的工作代码。

这个问题源于我之前使用 MIT 的开放课件学习 Python/CS 时提出的问题。 -- See my previous question here --

我正在使用以下代码来列出每月付款和其他事项的列表。然而，在循环结束时，我需要给出当月已支付的总金额的运行总计。

原始代码

balance = float(raw_input("Outstanding Balance: "))
interestRate = float(raw_input("Interest Rate: "))
minPayRate = float(raw_input("Minimum Monthly Payment Rate: "))

for month in xrange(1, 12+1):
    interestPaid = round(interestRate / 12.0 * balance, 2)
    minPayment = round(minPayRate * balance, 2)
    principalPaid = round(minPayment - interestPaid, 2)
    remainingBalance = round(balance - principalPaid, 2)


    print 'Month: %d' % (month,)
    print 'Minimum monthly payment: %.2f' % (minPayment,)
    print 'Principle paid: %.2f' % (principalPaid,)
    print 'Remaining balance: %.2f' % (remainingBalance,)

    balance = remainingBalance

    if month in xrange(12, 12+1):
        print 'RESULTS'
        print 'Total amount paid: '
        print 'Remaining balance: %.2f' % (remainingBalance,)

问题是我无法弄清楚如何保持支付金额的累计总额。我尝试添加 totalPaid = round(interestPaid +principalPaid, 2) 但这只会导致一个月的总计，我似乎无法让它保留每个月的该值，然后将它们全部添加放在最后打印出来。

我还知道结果金额应该是 1131.12

我发现了许多通过列表知道每个值时执行此操作的示例，但我似乎无法正确推断。

固定代码

balance = float(raw_input("Outstanding Balance: "))
interestRate = float(raw_input("Interest Rate: "))
minPayRate = float(raw_input("Minimum Monthly Payment Rate: "))
totalPaid = 0

for month in xrange(1, 12+1):
    interestPaid = round(interestRate / 12.0 * balance, 2)
    minPayment = round(minPayRate * balance, 2)
    principalPaid = round(minPayment - interestPaid, 2)
    remainingBalance = round(balance - principalPaid, 2)
    totalPaid += round(minPayment, 2)

    print 'Month: %d' % (month,)
    print 'Minimum monthly payment: %.2f' % (minPayment,)
    print 'Principle paid: %.2f' % (principalPaid,)
    print 'Remaining balance: %.2f' % (remainingBalance,)

    balance = remainingBalance

    if month in xrange(12, 12+1):
        print 'RESULTS'
        print 'Total amount paid: %.2f' % (totalPaid,)
        print 'Remaining balance: %.2f' % (remainingBalance,)

Answer 1

在循环之前，初始化一个变量来累加值:

total_paid = 0

然后，在循环体中添加适当的数量。您可以使用 += 运算符添加到现有变量，例如

total_paid += 1

是total_paid =total_paid + 1的缩写形式。您不想每次迭代都为 total_paid 提供新值，而是希望添加到其现有值。

我不确定您的问题的具体情况，但这是循环时累积值的一般形式。