What does isU of preg_match in php represent?

This article mainly introduces the meaning of isU of preg_match in php. Interested friends can refer to it. I hope it will be helpful to everyone.

isU means case separation, s here does not include the newline character, and U reverses the value of the number of matches so that it is not a default repetition. This is probably the case when we read the article.

/(.*)/isU after the regular expression, what does the "isU" parameter mean?

This is the modifier in the regular expression.

i searches for both uppercase and lowercase letters, and

s is a dot (.) that matches all characters, including newlines. If If s is not set, the newline character is not included.

U reverses the value of the number of matches so that it is not repeated by default, but becomes repeated when followed by "?"

Example

preg_match In the compatible regular expression syntax, b represents the word boundary

So: The following should be possible? ? ?

$a="test,admin,abc";
$b="te";
$exist=preg_match("/b{$b}b/",$a);
if($exist)
{
echo "存在";
}else
{
echo "不存在";
}

Look at the relevant instructions

Copy code The code is as follows:

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

preg_match() returns the number of times pattern is matched. Either 0 times (no match) or 1 time, since preg_match() will stop searching after the first match. preg_match_all(), on the contrary, will search until the end of subject. preg_match() returns false on error.

Example:

<?php
$a = "abcdefgabcdefaaag";
preg_match(&#39;|abc([a-z]+)g|isu&#39;,$a,$out1);
preg_match_all(&#39;|abc([s]+)g|isu&#39;,$a,$out2);
echo "<pre class="brush:php;toolbar:false">";
print_r($out1);
print_r($out2);
echo "

"; ?>

Writing:

The difference between using double quotes and single quotes

<?php
preg_match_all("/href="(.*)"/isu",$contents,$out);
preg_match_all(&#39;|href="(.*)"|isu&#39;,$contents,$out);
?>

Summary: The above is the text The entire content of this article is hoped to be helpful to everyone's study.

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