您不能分两步来做吗?换句话说，删除空格，然后替换< pre>".与< pre> \ n"和</pre>"一起使用

Can''t you do it in two steps? In other words, remove the whitespace and then replace "<pre>" with "<pre>\n" and "</pre>" with "\n</pre>".

，您可以找到在打开PRE(不紧随其后的PRE)之后不存在且不存在的所有空白在关闭PRE之前存在(不是在开始PRE之前).这将需要负的前瞻性和负性的后瞻性，而它们本身又包含负的前瞻性和负性的后瞻性.我从来没有尝试过将否定的前瞻性/后顾之忧结合在一起，所以我不确定它是否会起作用，但是似乎这是可行的方法.我会让您找出正则表达式，但伪正则表达式将是这样的:

You can find all whitespace that does not exist after an opening PRE (that isn''t followed by a closing PRE) and that does not exist before a closing PRE (that isn''t preceeded by an opening PRE). That would require a negative lookahead and a negative lookbehind that themselves contain a negative lookahead and a negative lookbehind. I''ve never tried combining negative lookaheads/lookbehinds like that, so I''m not sure it would work, but it seems like that would be the way to go. I''ll let you figure out the regex, but pseudo-regex would be something like this:

(must not contain a PRE that is not followed by a /PRE)
(?<=(.|\n)*)
whitespace
(?=(.|\n)*)
(must not contain a /PRE that is not preceeded by a PRE)

这是一个看起来很消极的样子:

Here is what a negative lookbehind looks like:

(?<!\<PRE\>)

这是一个负面的前瞻样子:

Here is what a negative lookahead looks like:

(?!\<\/PRE\>)

您必须做一些测试才能使用嵌套，因为我不确定它是如何工作的.

查看此参考，以获取更多C#正则表达式帮助.

You''ll have to do some testing to play with the nesting, as I am not quite sure how that works.

Check out this reference for more C# regex help.