正则表达式中的自定义单词边界 [英] Custom word boundaries in regular expression

问题描述

我正在尝试使用正则表达式匹配单词，但遗憾的是单词边界字符 (\b) 没有包含足够的字符，因此我想添加更多字符.(在这种情况下，+"字符)

I am trying to match words using a regular expression, but sadly the word boundary character (\b) does not include enough characters for my taste, so I want to add more. (in that precise case, the "+" character)

这是我曾经拥有的(它是 C#，但不是很相关):

Here is what I used to have (it is C# but not very relevant) :

string expression = Regex.Escape(word);
Regex regExp = new Regex(@"\b" + expression + @"\b", RegexOptions.IgnoreCase);

这个特定的正则表达式与C++"不匹配，我认为它真的很糟糕.所以我尝试在字符类中使用 \w 字符，以及 + 字符:

This particular regex did not match "C++" and I thought it was a real bummer. So I tried using the \w character in a character class that way, along with the + character :

string expression = Regex.Escape(word);
Regex regExp = new Regex(@"(?![\w\+])" + expression + @"(?![\w\+])", RegexOptions.IgnoreCase);

但是现在，没有任何东西匹配...是不是我遗漏了什么?

But now, nothing gets matched... is there something I am missing?

推荐答案

(字符类中无需转义+)

问题是您首先使用负向后视，而您应该使用负向后视.试试:

The problem is that you use a negative lookahead first whereas you should use a negative lookbehind. Try:

@"(?<![\w+])" + expression + @"(?![\w+])"

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