Phpemail Regular Expression explanation-PHP source code

This article only briefly introduces the e-mail Regular Expression in php. For more information, see. This article only briefly introduces the e-mail Regular Expression in php. For more information, see.

Script ec (2); script

General e-mail, such as zhangshan@163.com, abc@sina.com.cn such as some common form of the line, but in some of our company's customers mailbox but there are some zhangshna.Mr@163.com, abc_Wang.dd@sian.com, abc_Wang.dd.cc@sian.com this kind of similar form, there are points before the @ symbol ., I used it for use, but I can't do it now. I have to study Regular Expressions myself.

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Original Regular Expression

The Code is as follows:
/^ [A-zA-Z0-9 _-] + @ [a-zA-Z0-9 _-] + (. [a-zA-Z0-9 _-] +) + $ /;

The modified regular expression based on my actual situation

The Code is as follows:
/^ (W) + (. w +) * @ (w) + (. w {2, 3}) {1, 3}) $ /; Or /^ (W) + (. w +) * @ (w) + (. w +) $ /;

First, start with the name and divide it:
(1) email prefixes on the left: letters, numbers, underscores, points, and minus signs (can only start and end with a number or letter)
(2) Right domain name rules-letters, numbers, and minus signs (can only begin with a number and a letter, and cannot exceed 63 characters)

Now that the rules are ready, the rest is matching, hoping to avoid a "bad guy" as much as possible ":

The Code is as follows:
[A-zd] ([a-zd _. -] * [a-zd]) * @ ([a-zd] [a-zd-] {0, 61} [a-zd].) {1, 3} [a-z] {2, 6} ([.] [a-z] {2, 3 })? Right side Add ^ $ I:/^ [a-z0-9] ([a-z0-9-_.] * [a-z0-9]) * @ ([a-z0-9] [a-z0-9-] {} [a-z0-9].) {1, 3} [a-z] {2, 6} ([.] [a-z] {2, 6 })? $/I

I tried PHP and it worked well, that is, some problems still occurred in SQL statements, but it basically met my requirements.
Character Description:
^: Match the start position of the input.
: Mark the next character as a special character or literal value.
*: Match the first character Zero or several times.
+: Match the previous character once or multiple times.
(Pattern) matches the pattern and remembers the matching.
X | y: matches x or y.
[A-z]: a character in a certain range. Matches any character in the specified range.
W: matches any word characters, including underscores.

{N, m} matches at least n times and at most m times
$: Matches the end of the input.