转义字符串以在正则表达式中使用
我想在正则表达式中使用存储在变量中的字符串。 （在 PHP 中）转义字符串以便在 (PCRE) 正则表达式中使用的最佳方法是什么？
例如，
$text = 'm/z'; // this is the text I want to use as part of my regular expression
$text_regexp = '#' . $text . '#i'; // this is my regular expression
会给出
$text_regexp = '#m/z#i';
But I would Want 以下正则表达式：
$text_regexp = '#m\/z#i';
这是一个人为的示例，但我想简单地说明这一点。
Possible Duplicate:
Is there a PHP function that can escape regex patterns before they are applied?
I want to use a string stored in a variable in a regular expression. What's the best way (in PHP) to escape a string for use in a (PCRE) regular expression?
For example,
$text = 'm/z'; // this is the text I want to use as part of my regular expression
$text_regexp = '#' . $text . '#i'; // this is my regular expression
Would give
$text_regexp = '#m/z#i';
But I would want the following regular expression:
$text_regexp = '#m\/z#i';
This is a contrived example, but I wanted to illustrate the point simply.
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评论（4）
preg_quote
来自手册：
您还可以将分隔符作为第二个参数传递，它也会被转义。但是，如果您使用
#作为分隔符，则无需转义/preg_quote
From the manual:
You can also pass the delimiter as the second parameter and it will also be escaped. However, if you're using
#as your delimiter, then there's no need to escape/您必须使用
preg_quote函数：必须作为整个单词匹配的
$keyword示例：You must use the
preg_quotefunction:Example of a
$keywordthat must match as a whole word:检查这个。您可以使用 preg_quote();。
Check this. You can use preg_quote();.
所有这些答案都是正确的，只有元字符需要转义。
可惜 php 没有像 preg_match([operator]/$var/) 这样的正则表达式运算符，因此分隔符可以作为引用代理。这样 delimeter 就不必在外部 $var 中引用。 （Perl 有 m//,s/// 或 =~ 运算符）
preg_quote 是一个很好的方法，不幸的是，有时你想匹配文字 '\char' 而不将其转义为 '\char'实例，并逃避其余的。 preg_quote() 的选择不多。
您可以从字面上设置自己的 php 函数来引用元字符（或在 preg_quote() 之后去掉引号）。
就像将所有
/([{}\[\]()^\$.|*+?\\<>$delim])/替换为\\$1或其他东西。设置 $delim，和/或删除可能的转义符或任何其他您不想转义的元字符。只是我的 $.02
All these answers are correct, only the metachars need to be escaped.
Its kind of too bad that php doesen't have a regex operator like preg_match([operator]/$var/) so the delimeters could be the quoting agent. This way delimeter wouldn't have to be quoted in an external $var. (Perl has this with m//,s/// or =~ operators)
The preg_quote is a nice way to do this, unfortunately, sometimes you want to match literal '\char' without it being escaped to '\char' for instance, and escape the rest. Not many choices with preg_quote().
You could literally set up your own php functions that does quoting of metachars (or take off a quote after preg_quote() ).
like a replace all
/([{}\[\]()^\$.|*+?\\<>$delim])/with\\$1or something. Set the $delim, and/or take out possibly the escape or any other metachars you don't want escaped.Just my $.02