Regular Expression Function preg in PHP

Preg_match (); used for regular expression matching, and only match once preg_match_all (); used for regular expression matching, all compliant with the rule will be matched preg_replace (); regular Expression replacement function preg_splite (); Regular Expression division function preg_match (mode, stringsubject, arraymatches)

Preg_match (); // used for regular expression matching, and only matches preg_match_all () once; // used for regular expression matching, preg_replace () will be matched for all compliant rules; // The regular expression replacement function preg_splite (); // The regular expression division function preg_match (mode, string subject, arraymatches)

Preg_match (); // used for regular expression matching only once

Preg_match_all (); // used for regular expression matching. All matching rules are matched.

Preg_replace (); // Regular Expression replacement function

Preg_splite (); // Regular Expression division Function

Preg_match (mode, string subject, arraymatches)

Here, mode is a regular rule, string subject is the string to be matched, and arraymatches is the matching result array.

Example:

Output:

Array ( [0] => 9 ) 

Preg_match_all (mode, string subject, arraymatches)

This function is similar to the preg_match_all () function, but it matches all the required content and stores it in a string.

Example:

Output:

Array ( [0] => Array ( [0] => 8 [1] => 8 [2] => 9 [3] => 9 [4] => 9 ) ) 

Preg_replace (mixed pattern, mixed replacement, mixed subject [, int limit])

Use regular expressions to replace related content, similar to the previously learned str_replace string replacement, but the function is better than it.

Features: 1. The replacement content can be a regular or array regular

2. The replacement content can be replaced by the modifier e.

Purpose: replace some complicated content and use it for content conversion.

Example 1 -- array regular:

 Author: {author}
Url: {url} "; echo"
 "; If ($ tag = preg_replace ($ mode, $ re, $ str) {echo $ tag;} else {echo" cannot be replaced! ";}?>

Output:

Title: code cloud Author: qianshou address: http://codecloud.duapp.com/

Example 2 -- replace the ubb code:

Output:

Welcome to my blog: http://blog.csdn.net/qsyzb

Preg_split (string pattern, string subject [, intlimit [, int flags])

Regular expressions are used to cut related content. Similar to the previously learned explode cut function, explode only has limitations in one way.

Example:

Output:

Array(    [0] => one    [1] => two    [2] => three    [3] => four)