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This article will explain in detail how to check the regular expression of email. The editor thinks it is very practical, so I share it for you as a reference. I hope you can get something after reading this article.

How to verify an email address. There are three parts in a complete email address: the POP3 user name (everything to the left of @), @, and the server name (the rest). The user name can contain uppercase and lowercase letters Arabic numerals, period ('.'), minus sign ('-'), and and underscore ('_'). The server name also conforms to this rule, except for the underscore.

Check the discussion of email's regular expressions:

Now, neither the beginning nor the end of the user name can be a period. The same is true of servers. And you can't have two consecutive periods with at least one character between them, so now let's take a look at how to write a matching pattern for the user name:

^ [_ a-zA-Z0-9 -] + $

The existence of a full stop is not allowed yet. Let's add it:

^ [_ a-zA-Z0-9 -] + (\ .[ _ a-zA-Z0-9 -] +) * $

It means: "start with at least one canonical character (except. Unexpected), followed by 0 or more strings that begin with a dot."

Check the implementation of regular expressions for email:

To simplify, we can replace ereg () with eregi (). Eregi () is case-insensitive, so we don't need to specify two ranges "Amurz" and "Amurz"-we just need to specify one:

^ [_ a-z0-9 -] + (\ .[ _ a-z0-9 -] +) * $

The name of the following server is the same, but remove the underscore:

^ [a-z0-9 -] + (\ .[ a-z0-9 -] +) * $

Done. Now you just need to connect the two parts with "@":

^ [_ a-z0-9 -] + (\ .[ _ a-z0-9 -] +) * @ [a-z0-9 -] + (\ .[ a-z0-9 -] +) * $

This is the complete email authentication matching pattern, just call the

Eregi ('^ [_ a-z0-9 -] + (\ .[ _ a-z0-9 -] +) * @ [a-z0-9 -] + (\ .[ a-z0-9 -] +) * $', $eamil)

You can get whether it is email or not.

This is the end of this article on "how to check the regular expression of email". I hope the above content can be of some help to you, so that you can learn more knowledge. if you think the article is good, please share it for more people to see.

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