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 $a = "abcdefgabcdefaaag"; preg_match('|abc([a-z]+)g|isu',$a,$out1); preg_match_all('|abc([s]+)g|isu',$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,$out); preg_match_all('|href="(.*)"|isu',$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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