电子邮件的冲突正则表达式（Python）

Question

I'm trying to grab both usernames (such as abc123@) and emails (such as (abc123@company.com) in the same Pythonic regex.

Here's an example statement:

abc123@ is a researcher at abc123@company.com doing cool work.

Regex used:

For username:

re.match("^([A-Za-z])+([@]){1}$")

For email:

re.match("^([A-Za-z0-9-_])+(@company.com){1}$")

Most cases, what happens is username gets grabbed but not email address (trying to grab them as two separate entities) - any ideas what's going on?

Answer 1

Actually you have a lot of groups and repetition counts and start/end boundaries in your regexes that are not really necessary. These 2 are just enough to find each in the input string.

For user: [A-Za-z0-9]+@

For email: [A-Za-z0-9-_]+@company.com

If, however, you want your groupings, these versions that will work:

For user: ([A-Za-z0-9])+(@)

For email: ([A-Za-z0-9-_]+(@company.com)

Disclaimer: I have tested this only on Java, as I am not so familiar with Python.

Answer 2

In your patterns you use anchors ^ and $ to assert the start and end of the string.

Removing the anchors, will leave this for the username pattern ([A-Za-z])+([@]){1}

Here, you can omit the {1} and the capture groups. Note that in the example, abc123@ has digits that you are not matching.

Still, using [A-Za-z0-9]+@ will get a partial match in the email abc123@company.com To prevent that, you can use a right hand whitespace boundary.

The username pattern might look like

\b[A-Za-z0-9]+@(?!\S)

• \b A word boundary
• [A-Za-z0-9]+ Match 1+ occurrences of the listed (including the digits)
• @ Match literally
• (?!\S) Negative lookahead, assert not a non whitspace char to the right

Regex demo

For the email address, using a character class like [A-Za-z0-9-_] is quite strict.

If you want a broad match, you might use:

[^\s@]+@[^\s@]+\.[a-z]{2,}

Regex demo