了解Python中的研究

Question

I am trying to allow users to Enter alphanumerics,underscores and spaces for a name. I've been using if not re.search(r'^[\\w-]+$', name): to check if the name has anything other than alphanumerics,underscores and spaces. But here I can just enter one word, not multiple. What am I doing wrong?

Answer 1

You're not doing anything obviously wrong. Your question isn't totally clear either, so I'll try to address a couple of the possible issues.

Why is only one word accepted by the regex?

In your regex, you have \\w , which according to the re documentation , is just alphanumeric characters and underscore. What you have not included is the space character, so any name with a space (including if it's separating first and last name) will be matched by your regular expression, and therefore turned to False by the not . What you should do to check if there are any non-alphanumeric characters/underscores/spaces is the following:

if not re.search(r'^[\w- ]+$', name):

Or, if you also for some reason are concerned about newlines ( \\n ) or tabs ( \\t ) and other kinds of whitespace:

if not re.search(r'^[\w\s- ]+$', name):

Why can I only check one name at a time?

That's because the regex will only search one string at a time. If you want to have it check multiple names, you should run the regular expression against each name, in a format like this:

# assuming name_list is a list of name strings
for name in name_list:
    if not re.search(r'^[\w- ]+$', name):
        # do whatever

Answer 2

Your regex doesn't allow spaces (instead it allows dashes which you didn't mention in your question).

if not re.search(r'^[\w ]+$', name):

only allows ASCII letters, digits, underscore and spaces (and requires at least one character).

Answer 3

You need to learn a little bit about regular expressions.

I personally started from Google classes and it was good enough to read the docs .