preg_match regular expression to determine user name_PHP tutorial

Question
Regular expression to determine username
Solution
preg_match('/'/^s*$|^c:\con\con$|[%,*"st&'\]/', $username)


How do you understand copying code?

Thank you everyone

Copy PHP content to clipboard PHP code: [%,*"st&'\]


This part can basically be understood, asterisk, double quotation mark, space character, tab character, less than, greater than, &, single quotation mark, but why use two backslashes?

And what do the last four backslashes mean?

[ ]


Reference answer
[img]http://www.111cn.cn/bbs/images/smilies/default/funk.gif[/img]
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Usernames with symbols, whitespace characters, and line breaks are prohibited.

I feel like the regular author is a bit perverted.
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I don’t quite understand..Explain.
^s*$|^c:.
^ What does it mean
Why use two s
c:
What does it mean again
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/^

The strangest thing is here. ^ is placed in the middle of the expression, I really can’t think of what it means..
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s*

Then why use two
here? This is a single quote. Logically speaking, one is enough
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Du Jiang's book has talked about it. s t r are all there...
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Can’t you answer directly? [img]http://www.111cn.cn/bbs/images/smilies/default/42.gif[/img]
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con\con What does this do?
Reference answer
Can you tell me what you know?

http://www.bkjia.com/PHPjc/632587.htmlwww.bkjia.comtruehttp: //www.bkjia.com/PHPjc/632587.htmlTechArticleRegular expression solution to the problem of judging username preg_match('/'/^s*$|^c: \con\con$|[%,*"st '\] This part can basically be understood, * sign, double quotation mark, space character, tab character,...