Regular expressions: mailbox matching

Format Overview

Email address conforms to “ name @ domain name ” The rules . character “@” In the email address “ name ” and “ domain name ” Between , The email address name can only be made up of English letters 、 Numbers 、 Underline composition , Domain names are only allowed by English letters 、 Numbers 、“.”（ Order number ） form .

such as ,[email protected]、[email protected] It is the mailbox that conforms to the above rules .

Mode description

[\w][email protected][A-Za-z]+(\.[A-Za-z0-9]+){1,2}

In two parts , The first part [\w]+ The name used to match the mailbox , Second part [\w]+(.[A-Za-z]+){1,2} Used to match the domain name .

\w Means match number 、 Letter 、 Underline ,[\w]+ Indicates matching one or more numbers 、 Letter 、 Underline ;[A-Za-z] Used to match a letter ,[A-Za-z]+ Used to match one or more letters ,.[A-Za-z]+ Used to match to .（ Order number ） Start with one or more letters ,{1,2} Represents a matching expression (.[A-Za-z]+) Once or twice .

Be careful , This regular expression is not unique . There can be other forms ：

\b[\w][email protected][A-Za-z]+(\.[A-Za-z0-9]+){1,2}\b

^\[email protected][A-Za-z]+(\.[A-Za-z0-9]+){1,}$

Examples of use

>>> import re
>>> pattern = r"[\w][email protected][A-Za-z]+(\.[A-Za-z0-9]+){1,2}\b"
#  Conform to the format mailbox number 
>>> email = "[email protected]"
>>> re.match(pattern, email)
<re.Match object; span=(0, 16), match='[email protected]m'>
#  Email number that does not conform to the format , Contains special characters +
>>> email = "[email protected]"
>>> re.match(pattern, email)
None