Python: 在循环中对变量执行用户定义的加法

Question

这是我正在研究的更大 "vending machine" 的一部分的模块。不过，我运行遇到了一些问题。如果他们支付的金额不够（$1.75），他们将被要求输入额外的金额。我的部分问题是我不知道我应该做什么操作来改变循环内的赤字。我尝试过的所有事情都导致了 "input expected at most 1 arguments, got 3" 等错误。

selection = 5
loopCount = 0
deposit = 0
cost = 1.75
print("It costs $",cost,".")
deposit = float(input("Enter your money amount (e.g. 1.5 for .50, .50 for [=11=].50, etc.):\n--\n"))
deficit = cost - deposit
change = deposit - cost
if deposit < cost:
    while deficit > 0 and loopCount < 1:
        ??? = float(input("Please enter an additional $",deficit,"."))
        loopCount += 1
if deposit >= cost:
    print("Thank you for purchasing item#",selection,". Your change is $",change,".")

Answer 1

假设您不想在他们支付足够的钱之前打破循环，您可以这样做：

while abs(deficit) < cost:
    added = float(input("Please enter an additional $",deficit,"."))
    deficit = cost - deposit - added

abs 函数将输出绝对值，因此您可以将其直接与成本进行比较。

不过需要注意的是，您可能需要对输入进行错误检查。此外，如果您确实希望能够为用户提供一种机制来打破循环，您可以添加一个布尔值 true 或 false（而不是循环计数），它附加到一些其他输入，如 "Do you want to insert more money? y or n"

Answer 2

这对我有用。请务必增加 loopCount，因为现在，它不会循环多次。

selection = 5
loopCount = 0
deposit = 0
cost = 1.75
print("It costs $",cost,".")
deposit = float(input("Enter your money amount (e.g. 1.5 for .50, .50 for [=10=].50, etc.):\n--\n"))
deficit = cost - deposit
change = deposit - cost
if deposit < cost:
    while deficit > 0 and loopCount < 1:
        deficit -= float(input("Please enter an additional ${}.".format(deficit)))
        loopCount += 1
if deposit >= cost:
    print("Thank you for purchasing item#",selection,". Your change is $",change,".")

Python: 在循环中对变量执行用户定义的加法

Python: Performing user-defined addition to a variable in a loop

python

variables

loops

addition