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How to escape regular expressions in PHP

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How to escape regular expressions in PHP

    本文主要讲述了如何利用 preg_quote() 函数用来对正则表达式字符串进行转义

1.语法:

string preg_quote ( string $str [, string $delimiter = NULL ] )
  • $str: 输入字符串。

  • $delimiter: 如果指定了可选参数 delimiter,它也会被转义。这通常用于 转义 PCRE 函数使用的分隔符。 / 是最通用的分隔符。

        preg_quote()需要参数 str 并向其中 每个正则表达式语法中的字符前增加一个反斜线。 这通常用于你有一些运行时字符串 需要作为正则表达式进行匹配的时候。

        目前支持的正则表达式特殊字符有: . \ + * ? [ ^ ] $ ( ) { } = ! | : - #

PS:字符 # 7.3.0版本被增加为需要转义的。    

2.示例:

<?php

$keywords = &#39;$40 for a g3/400&#39;;
$keywords = preg_quote($keywords, &#39;/&#39;);
echo $keywords; // 返回 \$40 for a g3\/400
?>

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