PCRE 函数

preg_filter — 执行一个正则表达式搜索和替换
preg_grep — 返回匹配模式的数组条目
preg_last_error_msg — Returns the error message of the last PCRE regex execution
preg_last_error — 返回最后一个PCRE正则执行产生的错误代码
preg_match_all — 执行一个全局正则表达式匹配
preg_match — 执行匹配正则表达式
preg_quote — 转义正则表达式字符
preg_replace_callback_array — Perform a regular expression search and replace using callbacks
preg_replace_callback — 执行一个正则表达式搜索并且使用一个回调进行替换
preg_replace — 执行一个正则表达式的搜索和替换
preg_split — 通过一个正则表达式分隔字符串

add a note

User Contributed Notes 3 notes

down

steve at stevedix dot de ¶

17 years ago


Something to bear in mind is that regex is actually a declarative programming language like prolog : your regex is a set of rules which the regex interpreter tries to match against a string.   During this matching, the interpreter will assume certain things, and continue assuming them until it comes up against a failure to match, which then causes it to backtrack.  Regex assumes "greedy matching" unless explicitly told not to, which can cause a lot of backtracking.  A general rule of thumb is that the more backtracking, the slower the matching process.

It is therefore vital, if you are trying to optimise your program to run quickly (and if you can't do without regex), to optimise your regexes to match quickly.

I recommend the use of a tool such as "The Regex Coach" to debug your regex strings.

http://weitz.de/files/regex-coach.exe (Windows installer) http://weitz.de/files/regex-coach.tgz (Linux tar archive)

down

stronk7 at moodle dot org ¶

14 years ago


One comment about 5.2.x and the pcre.backtrack_limit:

Note that this setting wasn't present under previous PHP releases and the behaviour (or limit) under those releases was, in practise,  higher so all these PCRE functions were able to "capture" longer strings.

With the arrival of the setting, defaulting to 100000 (less than 100K), you won't be able to match/capture strings over that size using, for example "ungreedy" modifiers.

So, in a lot of situations, you'll need to raise that (very small IMO) limit.

The worst part is that PHP simply won't match/capture those strings over pcre.backtrack_limit and will it be 100% silent about that (I think that throwing some NOTICE/WARNING if raised could help a lot to developers).

There is a lot of people suffering this changed behaviour from I've read on forums, bugs and so on).

Hope this note helps, ciao :-)

down

-3

Svoop ¶

13 years ago


I have written a short introduction and a colorful cheat sheet for Perl Compatible Regular Expressions (PCRE):

http://www.bitcetera.com/en/techblog/2008/04/01/regex-in-a-nutshell/

add a note

官方地址：https://www.php.net/manual/en/ref.pcre.php

有任何技术问题请点击这里网站运营推广招聘

IT PHP 编程语言 Linux 开发编程科技 Elasticsearch HTML/CSS/XML 网络数据库 JAVA 面试 NoSQL C/C++ Golang Git 算法操作系统正则表达式 Redis 互联网 MySql JavaScript 运维软件国际架构设计 Mac OS TCP/IP Excel Vim Windows Socket Oracle VR MongoDB Python 运营 MemCache 商业硬件电子娱乐设计 nginx 摄影游戏 WordPress HTTP 团建数码电器

php7 安装fileinfo扩展 preg_split — 通过一个正则表达式分隔字符串 php位值,解决 PHP 中 usort 在值相同时改变原始位置的问题 [PHP] inet_pton/inet_ntop IP地址转换函数 PHP 8.1 [鸟哥]PHP_INT_MIN 和 -9223372036854775808 ADORecordSet对象 adodb手册 opcache预加载 Composer的Packagist资源 array_multisort() 多字段排序 PHPMailer设置utf8 PHPMailer字符集CharSet PHP json解析（json_decode）页面工具 mysql面试题 [原创]诡异的php-fpm超时问题 php中几种注释规范纯php实现DES以及TripleDES加密算法 php 修改图片大小支持php7的性能采集扩展 PHP mkdir()写出来的权限与mode值不符合

略微加速

PHP官方手册 - 互联网笔记

PCRE 函数

目录

User Contributed Notes 3 notes