正则表达式删除HTML，但有例外

Question

In C#, I have the following regex expression to remove HTML from a string:

var regex = new Regex("<[^>]*(>|$)");
return regex.Replace(input, match => "");

There are some cases where we need to allow for double >> and << . How do I change the above expression to simply skip these double angled brackets?

Answer 1

Not sure why the $ at the end is in there too, but anyway... negative lookahead and lookbehind can solve this problem:

Regex regex = new Regex("(?<![<])<[^<>]+>(?![>])");
return regex.Replace(input, String.Empty);

This will match any < not preceded by another <, then the content, and then any > not followed by another >.