What does the / (. *) / isU after the php regular mean?

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What does the parameter "isU" mean by / (. *) / isU after the regular?

This is the modifier in the rule.

I look up uppercase and lowercase letters at the same time

S is a dot (.) Matches all characters, including newline characters. If s is not set, newline characters are not included.

U reverses the value of the matching number so that it is not the default repetition, but follows "?" To become repetitive.

Example

B stands for word boundaries in preg_match-compatible regular expression syntax

So: the following should be OK?

$a = "test,admin,abc"; $b = "te"; $exist=preg_match ("/ b {$b} b /", $a); if ($exist) {echo "exist";} else {echo "does not exist";}

Take a look at the relevant instructions

The copy code is as follows:

Int preg_match (string pattern, string subject [, array matches [, int flags]])

Preg_match () returns the number of times pattern matches. Either 0 times (no matches) or 1 time, because preg_match () stops searching after the first match. Preg_match_all (), by contrast, searches all the way to the end of subject. Preg_match () returns false if there is an error.

Example:

Written as follows:

The difference between double quotation marks and single quotation marks