如何在python中检查字符串仅包含数字和/? [英] How to I check that a string contains only digits and / in python?

问题描述

我试图检查一个仅包含/和数字的字符串，以用作一种验证形式，但是我找不到并做到这两种方式.自动取款机我有这个:

I am trying to check that a string contains only / and digits, to use as a form of validation, however I cannot find and way to do both. ATM I have this:

if Variable.isdigit() == False:

这适用于数字，但我还没有找到一种方法来检查斜线.

This works for the digits but I have not found a way to check also for the slashes.

推荐答案

有很多选项，如下所示.列表解析是一个不错的选择.

There are many options, as showed here. A nice one would be list comprehensions.

让我们考虑两个字符串，一个满足条件，另一个不满足:

Let's consider two strings, one that satisfies the criteria, other that doesn't:

>>> match = "123/456/"
>>> no_match = "123a456/"

我们可以使用 isdigit()和比较来检查它们的字符是否匹配:

We can check if a character of them matches by using isdigit() and comparation:

>>> match[0].isdigit() or match[0] == '/'
True

但是我们想知道所有字符是否匹配.我们可以使用列表理解:

But we want to know if all chars match. We can get a list of results by using list comprehensions:

>>> [c.isdigit() or c == '/' for c in match]
[True, True, True, True, True, True, True, True]
>>> [c.isdigit() or c == '/' for c in no_match]
[True, True, True, False, True, True, True, True]

请注意，不匹配字符串的列表在'a'字符的相同位置具有 False .

Note that the list of the non-matching string has False at the same position of the 'a' char.

由于我们希望所有 个字符匹配，因此我们可以使用

Since we want all chars to match, we can use the all() function. It expects a list of values; if at least one of them is false, then it returns false:

>>> all([c.isdigit() or c == '/' for c in match])
True
>>> all([c.isdigit() or c == '/' for c in no_match])
False

奖励积分

放入功能

您最好将其放在函数上:

Bonus points

Put on a function

You would be better to put it on a function:

>>> def digit_or_slash(s):
...     return all([c.isdigit() or c == '/' for c in s])
... 
>>> digit_or_slash(match)
True
>>> digit_or_slash(no_match)
False

生成器表达式

生成器表达式往往更有效:

Generator expressions

Generator expressions tend to be more efficient:

>>> def digit_or_slash(s):
...     return all(c.isdigit() or c == '/' for c in s)
... 

但是在您的情况下，它还是可以忽略不计的.

But in your case it is probably negligible anyway.

我希望使用 in 运算符，如下所示:

I would prefer to use the in operator, as below:

>>> def digit_or_slash(s):
...     return all(c in "0123456789/" for c in s)

请注意，这只是选项之一.遗憾的是，您的问题未能通过 Python推荐的禅宗(>>>导入此):

Note that this is only one of the options. Sadly, your problem fails this Zen of Python recommendation (>>> import this):

应该有一种(最好只有一种)明显的方法.

There should be one- and preferably only one -obvious way to do it.

但是没关系，现在您可以选择自己喜欢的任何东西了:)

But that's ok, now you can choose whatever you prefer :)

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