Question

我是Python的新手，它创建了一个程序，可以累加某人的动物数量。

如果用户输入字符串（例如，键入“五”或其他任何字符，程序将中断）。

我该怎么做才能阻止程序中断并使用户返回问题选项？

我创建了一个覆盖整数的循环和else语句。

loop = 1
while loop == 1:
    a = int(input(
    "Select A Question:"
    "Dog Question: '1'"
    "Cat Question: '2'"
    "Rabbit Question: '3'"
    "Calculate Total Animals: '4'"
    "Enter one of the above options 1-4:"))

if a == 1:
    f = int(input("How many doggos do you have?: "))
elif a == 2:
    h = int(input("How many cats do you have?: "))
elif a == 3:
    s = int(input("How many rabbits do you have?: "))
elif a == 4:
    loop = 0

else:
        print("Please enter a valid value e.g. '1', '2', '3'"
          "To add up your animals '4'")

Answer 1

首先，您无需分配loop = 1； while True就可以了。

接下来，原因是您试图将input()的结果转换为int ，无论是否可能。除非这样做，否则应该对它执行一些检查，并且仅在满足以下条件的情况下才对break进行循环检查，例如：

input_prompt = ("Select A Question:"
                "Dog Question: '1'"
                "Cat Question: '2'"
                "Rabbit Question: '3'"
                "Calculate Total Animals: '4'"
                "Enter one of the above options 1-4:")

while True:
    a = input(input_prompt)
    if a.isdigit() and 1 <= int(a) <= 4:
        a = int(a)
        break

    else:
        print("Please enter a valid value e.g. '1', '2', '3'"
              "To add up your animals '4'")

Answer 2

如果要防止程序中断，修复很简单。您只需要将输入代码更改为input（）而不是int（input（））。用int（）将输入括起来会强制用户输入为整数。

如果要将其返回给用户输入，请执行以下操作以检查它是否不是整数。

if a == 1:
    f = input("How many doggos do you have?: ")
    if not f.isdigit():
        pass

希望这会有所帮助！

Answer 3

尝试使用代码：

loop = 1
while loop == 1:
    try:
        a = int(input(
        "Select A Question:"
        "Dog Question: '1'"
        "Cat Question: '2'"
        "Rabbit Question: '3'"
        "Calculate Total Animals: '4'"
        "Enter one of the above options 1-4:"))
        loop = 0
    except:
        pass

if a == 1:
    f = int(input("How many doggos do you have?: "))
elif a == 2:
    h = int(input("How many cats do you have?: "))
elif a == 3:
    s = int(input("How many rabbits do you have?: "))
elif a == 4:
    loop = 0

else:
    print("Please enter a valid value e.g. '1', '2', '3'"
          "To add up your animals '4'")

Answer 4

最好，如果您只是刚开始输入字符串，然后尝试获取整数。这样，您的代码就不会很快失败。您可以像这样解决您的示例：

# you need to initialise the variables in order to avoid an error when 
# summing them up
number_of_dogs = 0
number_of_cats = 0
number_of_rabbits = 0

while True:
    # Ask for the desired mode after each 'secondary entry'
    a = input(
    "Select A Question:*' \n\
    Dog Question: '1' \n\
    Cat Question: '2' \n\
    Rabbit Question: '3' \n\
    Calculate Total Animals: '4' \n\
    Enter one of the above options 1-4:")

    if a is '1':
        # get the user input as a string
        dogs = input("How many doggos do you have?: ")
        try:
            # try to convert it (you can also combine this with the prior 
            # input(...) but then you're more likely to catch exceptions
            # you don't want to catch)
            number_of_dogs = int(dogs)
        except:
            print("please just enter a digit")
    elif a is '2':
        cats = input("How many cats do you have?: ")
        try:
            number_of_cats = int(cats)
        except:
            print("please just enter a digit")
    elif a is '3':
        rabits = input("How many rabbits do you have?: ")
        try:
            number_of_rabbits = int(rabits)
        except:
            print("please just enter a digit")
    elif a is '4':
        print("You have " 
            + str(number_of_dogs
                + number_of_cats
                + number_of_rabbits)
            + " animals")
        break

    else:
            print("Please enter a valid value e.g. '1', '2', '3'"
            "To add up your animals '4'")

还有一个小技巧，请尝试使用更多解释性的变量名，它使代码更具可读性。而且，您还可以在第一个输入语句中使用更多的逻辑选择：“狗”，“猫”等，而不是1，2，3 ...

如果用户输入字符串而不是整数，如何显示消息？

4 个答案: