使用正则表达式来确保字符串是字母数字加号的 Python 代码。- _
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Python code to use a regular expression to make sure a string is alphanumeric plus . - _
提问by Warlax
I looked and searched and couldn't find what I needed although I think it should be simple (if you have any Python experience, which I don't).
我查看并搜索并找不到我需要的东西，尽管我认为它应该很简单（如果您有任何 Python 经验，我没有）。
Given a string, I want to verify, in Python, that it contains ONLY alphanumeric characters: a-zA-Z0-9and ._-
给定一个字符串，我想在 Python 中验证它是否只包含字母数字字符：a-zA-Z0-9和._-
examples:
例子：
Accepted:
公认：
bill-gates
bill-gates
Steve_Jobs
Steve_Jobs
Micro.soft
Micro.soft
Rejected:
拒绝：
Bill gates-- no spaces allowed
Bill gates-- 不允许有空格
[email protected]-- @ is not alphanumeric
[email protected]-- @ 不是字母数字
I'm trying to use:
我正在尝试使用：
if re.match("^[a-zA-Z0-9_.-]+$", username) == True:
if re.match("^[a-zA-Z0-9_.-]+$", username) == True:
But that doesn't seem to do the job...
但这似乎并没有完成这项工作......
回答by Mark Rushakoff
re.matchdoes not return a boolean; it returns a MatchObjecton a match, or Noneon a non-match.
re.match不返回布尔值；它MatchObject在匹配或None不匹配时返回 a 。
>>> re.match("^[a-zA-Z0-9_.-]+$", "hello")
<_sre.SRE_Match object at 0xb7600250>
>>> re.match("^[a-zA-Z0-9_.-]+$", " ")
>>> print re.match("^[a-zA-Z0-9_.-]+$", " ")
None
So, you shouldn't do re.match(...) == True; rather, you should be checking re.match(...) is not Nonein this case, which can be further shortened to just if re.match(...).
所以，你不应该这样做re.match(...) == True；相反，您应该re.match(...) is not None在这种情况下进行检查，可以进一步缩短为 just if re.match(...)。
回答by Ignacio Vazquez-Abrams
Never use == Trueor == Falsein a comparison. Many types already have a bool equivalent which you should use instead:
切勿使用== True或== False进行比较。许多类型已经有一个 bool 等效项，您应该改用它：
if re.match("^[a-zA-Z0-9_.-]+$", username):
回答by Ignacio Vazquez-Abrams
Could also shorten it slightly to :
也可以稍微缩短为：
if re.match(r'^[\w.-]+$', username):
回答by sp_omer
I would consider this for a valid username:
1) Username must be 6-30 characters long
2) Username may only contain:
我会认为这是一个有效的用户名：
1) 用户名必须是 6-30 个字符长
2) 用户名只能包含：
- Uppercase and lowercase letters
- Numbers from 0-9 and
- Special characters _ - .
- 大写和小写字母
- 0-9 的数字和
- 特殊字符 _ - 。
3) Username may not:
3) 用户名不得：
Begin or finish with characters _ - .
Have more than one sequential character _ - . inside
以字符 _ - 开始或结束。
有多个连续字符 _ - 。里面
This would be example of usage:if re.match(r'^(?![-._])(?!.*[_.-]{2})[\w.-]{6,30}(?<![-._])$',username) is not None:
这将是使用示例：if re.match(r'^(?![-._])(?!.*[_.-]{2})[\w.-]{6,30}(?<![-._])$',username) is not None:
回答by fabrizioM
If you are going to use many regular expressions you can compile it for speed (or readability)
如果您打算使用许多正则表达式，您可以对其进行编译以提高速度（或可读性）
import re
ALPHANUM=re.compile('^[a-zA-Z0-9_.-]+$')
for u in users:
if ALPHANUM.match(u) is None:
print "invalid"
From the docs:
从文档：
The compiled versions of the most recent patterns passed to re.match(), re.search()or re.compile()are cached, so programs that use only a few regular expressions at a time needn't worry about compiling regular expressions.
最近模式的编译版本传递给re.match()，re.search()或者re.compile()被缓存起来，因此只有在一个时间不用担心编译正则表达式使用一些正则表达式的程序。
回答by Daniel Watson
I do my validation this way in my utils class:
我在我的 utils 类中以这种方式进行验证：
def valid_re(self, s, r):
reg = re.compile(r)
return reg.match(s)
Then I call the utils instance, and check this way:
然后我调用 utils 实例，并以这种方式检查：
if not utils.valid_re(username, r'^[a-zA-Z0-9_.-]+$'):
error = "Invalid username!"
