如何在python中为一个简单的计算器修复此命令

Question

first = input("What is your first number?(type x to do nothing) ")
second = input("What is your second number?(type x to do nothing) ")

if first == "x":
    first = None

if second == "x":
    second = None

if first and second == "x":
    print("You have not used any numbers. Disabling calculator...")
    sys.exit()

first = float(first)
second = float(second)

这是我的代码在计算器中的一部分，但它不喜欢按我希望的方式运行。

当用户在两个变量中输入“ x”时，我试图使python代码自行关闭。当我尝试这样做时，python向我发送一条错误消息：

TypeError: float() argument must be a string or a number, not 'NoneType'

有帮助吗？

Answer 1

要检查两个变量是否等于某个值，必须运行两个测试

if first=="x" and second=="x":

但是您已经将None修改为它们，所以它们不再是x，应该是以下内容

if first is None and second is None:

---

您有两个选择

1. 如果未给出仅默认值，则提供默认值

   if first == "x" and second == "x":
       print("You have not used any numbers. Disabling calculator...")
       sys.exit()
   elif first == "x":
       first = 0
   elif second == "x":
       second = 0
   
   first = float(first)
   second = float(second)
   

2. 即使只有2个是x，也要停止程序

   if first == "x" or second == "x":
       print("You have not used any numbers. Disabling calculator...")
       sys.exit()
   
   first = float(first)
   second = float(second)
   

---

因为不是问题，而是一个很好的建议，可以帮助您：验证该值是否为数字

any(map(str.isnumeric, [first, first.strip("-+")]))

• 测试值本身或没有符号的值
• 仅是数字：仅数字和点
• [any以获取它的值或不带符号的值

Answer 2

更改：如果第一和第二==“ x”：

至：如果第一和第二== None：