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This article mainly introduces how to use the preg match regular expression function in PHP. It has certain reference value. Interested friends can refer to it. I hope you will gain a lot after reading this article. Let Xiaobian take you to understand it together.

The preg_match() function is used to match regular expressions and returns 1 if successful, or 0 otherwise.

preg_match() stops matching after one successful match. If you want to match all the results, you need to use the preg_match_all() function.

Grammar:

preg_match (pattern , subject, matches) Parameter description pattern Regular expression subject Objects to be matched matches Optional, array storing matching results

Examples:

This instance matches capital letters followed by. A string of characters with spaces can only match up to J. Because preg_match() will stop matching after one successful match, and will not match again.

Output:

Array ( [0] => J. )

The following is an introduction to the preg_match string length problem

preg_match regular extraction target content, dead or alive problems, code measured dead.

Later, I suspected that PHP's preg_match has a string length limit, and sure enough, I found that the value of "pcre.backtrack_limit " is only set to 100000 by default.

Solution:

ini_set('pcre.backtrack_limit', 999999999);

Note: This parameter is available after PHP 5.2.0.

Pcre. recurrence_limit

pcre. recurrence_limit is the recursion limit of PCRE, which, if set to a large value, consumes all available stacks of processes and eventually causes PHP to crash.

You can also restrict it by modifying the configuration:

ini_set('pcre.recursion_limit', 99999);

In actual project applications, it is also best to set the memory limit: ini_set ('memory_limit','64 M'); , so that it is more stable.

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