How to use regex to implement string replacement in php

php method to use regular expressions to implement string replacement: first create a PHP sample file; then set the "s (PCRE_DOTALL)" modifier; finally use regular expressions to match the characters in the pattern to uppercase and lowercase letters. .

The operating environment of this tutorial: Windows 7 system, PHP version 5.6. This method is suitable for all brands of computers.

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PHP string regular replacement function preg_replace usage instructions

1. preg_replace( )

$msg = preg_replace("/<style>.+<\/style>/is", "", $msg); -----删除<style></style>和中间的部分
$msg = preg_replace("/<[^>]+>/", "", $msg); -----是删除<>和中间的内容
i (PCRE_CASELESS)

If this modifier is set, characters in the pattern will match both uppercase and lowercase letters.

s (PCRE_DOTALL)

If this modifier is set, the dot metacharacter (.) in the pattern matches all characters, including newlines. Without this setting, newline characters are not included. This is equivalent to Perl's /s modifier. Excluded character classes such as [^a] always match newlines, regardless of whether this modifier is set.

2. ereg() and eregi()

Note: The preg_match() function is usually a faster alternative than ereg()

eregi("<body([^>]+)>(.+)</body>",$data,$b)----察看$data中是否有body标签。如果有，把参数赋值$b[0]，中间部分赋值$b[1]。
bool ereg ( string pattern, string string [, array regs] )
int eregi ( string pattern, string string, array [regs] )

eregi() and ereg () is similar and has the same usage. The difference is that ereg() is case-sensitive, while eregi() is case-independent.

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