Python：通过在 function 之外操作变量来验证用户输入

Question

我对 python 有点陌生，并且有一个非常基本的了解。

我正在创建一个非常简单的程序，它可以作为 map 的决定。 用户输入 0 表示否，输入 1 表示是，以便继续向下判断 map 并最终得出结论。 对于每个决策，答案（0 或 1）都保存在一个新变量中。

我的问题：我创建了一个 function 来验证用户输入的响应是否有效。 每次我为每个新的决策/变量请求新的响应后，我都想使用这个 function。 例如，在第一个变量seq中，如果用户输入 2，则应输入验证 function 并进入循环，直到用户输入 0 或 1。但是，一旦输入 0 或 1，我不知道如何将该新值重新分配给seq以继续执行决定 map。

我尝试过：将 x 设置为全局，启动x = 0 ，将变量（即seq ）设置为全局，然后添加seq = valid_user_input(x)

任何帮助将不胜感激。 我正在寻找一个简单的解决方案，希望对我来说不太先进。 这是编辑我的代码的链接！ Repl.it map 程序

#Validation Function
def valid_user_input(x):

  while x != 1 and x != 0:
    x = int(input("Please answer the following question with [0 being no] and [1 being yes]\n"))
    print("x value is: ", x)
  return x

#Conditions/ Call Validation Function
seq = int(input("Is your equation in the {An} form or a list of terms?\n0. No]\n[1. Yes]\n"))
valid_user_input(seq) #CALL FUNCTION

if seq == 0: #seq no
  print("You have a series!\n")

  part = int(input("Is your equation in the form Sn?\n[1. Yes]\n[0. No]\n"))
  valid_user_input(part) #CALL FUNCTION

    if part == 0: #part no

    #Continue conditions...

    if part == 1: #part yes

if seq == 1: #seq yes
  print("You have a sequence!")

  tels = int(input("Do all terms cancel out except first and last term?\n[1. Yes]\n[0. No]\n"))
  valid_user_input(tels) #CALL FUNCTION

Answer 1

你设计你的 function 所以它有一个任务：返回 0 或 1 给给定的text （你的问题）：

def ask_01(text):
    """Asks text's content until either 0 or 1 are answered and returns that."""
    r = -1
    retry = False
    while r not in {0,1}:
        try:
            if retry:
                print("Wrong input")
            retry = True
            r = int(input(text + " Yes (1) or No (0)?"))
        except ValueError:  # if non-intergers are answered it gets cought here
            pass
    return r

weather_ok = ask_01("Ok Weather?")
happy = ask_01("Are you happy?")
print(weather_ok, happy)

并且只有在输入有效时才离开 function：

输入的输出：4,a,1,3,i,0

Ok Weather? Yes (1) or No (0)? 4
Wrong input
Ok Weather? Yes (1) or No (0)? a
Wrong input
Ok Weather? Yes (1) or No (0)? 1
Are you happy? Yes (1) or No (0)? 3
Wrong input
Are you happy? Yes (1) or No (0)? i
Wrong input
Are you happy? Yes (1) or No (0)? 0

1 0

更多关于验证：

• 要求用户输入，直到他们给出有效的响应

Answer 2

这是一个人为的例子。 我什至不建议这是做你想要实现的事情的好方法（删除prompt键值对感觉很糟糕） - 我在这里试图展示的是数据驱动的方法可能是可取的，因为它有助于减少 if 语句。

tree = {

    "prompt": "Do you have a cat (0) or a dog (1)?",

    "0": {
        "prompt": "Is your cat male (0) or female (1)?",
        "0": {"prompt": "You have a male cat!"},
        "1": {"prompt": "You have a female cat!"}
        },
    "1": {
        "prompt": "Is your dog male (0) or female (1)?",
        "0": {"prompt": "You have a male dog!"},
        "1": {"prompt": "You have a female dog!"}
        }

}

current_branch = tree
while True:
    print(current_branch["prompt"])
    del current_branch["prompt"]
    if not current_branch:
        break
    for key in current_branch:
        print(f">[{key}]")
    while True:
        user_input = input("Enter your selection: ")
        if user_input in current_branch:
            break
    current_branch = current_branch[user_input]

示例 Output：

Do you have a cat (0) or a dog (1)?
>[0]
>[1]
Enter your selection: asdf
Enter your selection: 3
Enter your selection: 2
Enter your selection: 1
Is your dog male (0) or female (1)?
>[0]
>[1]
Enter your selection: abcd
Enter your selection: a
Enter your selection: 0a
Enter your selection: 0
You have a male dog!
>>> 

Answer 3

我建议您提出一个问题，询问 class，您可以在其中处理每个问题的行为，并简化流程：

from dataclasses import dataclass


@dataclass
class Question:
    question: str
    answer: int = None

    def _validate(self, answer):
        if answer not in (0, 1):
            print("Please answer the following question with [0 being no] and [1 being yes]\n")
            raise ValueError

    def ask(self) -> int:
        self.answer = input(self.question)
        try:
            self.answer = int(self.answer)
            self._validate(self.answer)
        except ValueError:
            return self.ask()
        return self.answer


q1 = Question('Are you blue?')
q2 = Question('Do you like oceans?')
q3 = Question('Are you virtual?')

if q1.ask():
    if q2.ask():
        print('You are a dolphin')
    else:
        print('I don\'t know what you are')
else:
    if q3.ask():
        print('Get connected')
    else:
        print('I can\' help you')

# Also can access previous answers:
# q1.answer -> 0 or 1