错误消息：TypeError：不支持的操作数类型 -：'str' 和 'float' [关闭]

Question

我正在为我的 GCSE 课程编写一个程序，它的工作原理类似于自动售货机。我试图从重写的变量中减去一个变量，但由于某种原因它不起作用。帮忙？

This is my code:
credit=raw_input("Please input your change, CAREFUL! This Machine only accepts 10p,20p,50p and £1: ")
list1= ["1", "2", "3", "4", "5"]
price1=0.65
price2=0.70
price3=0.50
price4=0.70
price5=0.80
while (credit) == 0:
   (credit)=raw_input("Please input your change: ")
products = (" 1) Kinder Bueno\n 2) Doritos Chilli Heatwave\n 3) Nestle Yorkie Bar\n 4) Coca Cola(Can)\n 5) Volvic Stawberry Water")
print (credit)
print ("The product selection is the following")
print (products)
(selection)=raw_input("Please select a product: ")
if (selection) == (list1[0]):
   (new_credit)=int(credit-price1)
   print (new_credit)

Answer 1

在 python 中，你所有的 ( ) 都是多余的，我相信你真正的意思是。

credit = raw_input("Please input your change, CAREFUL! This Machine only accepts 10p,20p,50p and £1: ")
list1= ["1", "2", "3", "4", "5"]
price1 = 0.65
price2 = 0.70
price3 = 0.50
price4 = 0.70
price5 = 0.80
while credit == 0:
   credit = raw_input("Please input your change: ")
products = " 1) Kinder Bueno\n 2) Doritos Chilli Heatwave\n 3) Nestle Yorkie Bar\n 4) Coca Cola(Can)\n 5) Volvic Stawberry Water"
print credit
print "The product selection is the following"
print products
selection = raw_input("Please select a product: ")
if selection == list1[0]:
   new_credit = int(credit) - price1  # NOTE THE CHANGE HERE :)
   print new_credit

请注意上面的更改（除了删除多余的括号）。演员应该只关注功劳，而不是功劳不计价格。

注意

为了与 Python3 兼容，可能值得将括号放入您的 print 语句（因为 print 现在是一个函数），但对于 if / else / while 等控制流语句绝对不需要它们