Python除以0错误

问题描述

我当前正在使用以下Python代码：

I am currently using this Python code:

valid_chars = "0123456789-+/* \n";
while True:
    x = "x="
    y = input(" >> ")
    x += y
    if False in [c in valid_chars for c in y]:
        print("WARNING: Invalid Equation");
        continue;
    if(y == "end"):
        break
    exec(x)
    print(x)

当用户执行以下操作时崩溃：9/0。错误：

It crashes when the user does something like this: 9/0. Error:

ZeroDivisionError: division by zero

有哪些方法可以防止用户将某物除以零？

What are some ways that will prevent the user from dividing something by zero?

推荐答案

您可以除了 ZeroDivisionError 之外

x = "1/0"
try:
    exec(x)
except ZeroDivisionError:
    print ("WARNING: Invalid Equation")

如果您使用的是Python 2.x，则输入数据将在此处进行评估

If you are using Python 2.x, the input data will be evaluated here itself

y = input(" >> ")

因此，在Python 2中.x，您应该使用

so, in Python 2.x, you should be using

y = raw_input(" >> ")

除此之外，您可以改进这段代码

Apart from that, you can improve this piece of code

if False in [c in valid_chars for c in y]:

valid_chars = set("0123456789-+/* \n")    # We make this a set, because
if not all(c in valid_chars for c in y):  # c in valid_chars will be in O(1)

就像@gnibbler一样，在评论部分建议，如果条件可以这样写，则相同

As @gnibbler, suggested in the comments section, the same if condition can be written like this

if any(c not in valid_chars for c in y):  # c in valid_chars will be in O(1)

另一个建议是，无需使用分号来标记Python的行尾：）

Another suggestion would be, no need to use semi colons to mark the end of line in Python :)

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