What's wrong with my regex_问答_开发者_运维开发者技术经验分享

开发者 https://www.devze.com 2022-12-23 08:51 出处：网络

Yes I know its usually a bad idea to parse HTML using RegEx, but that aside can someone explain the fault here:

相关专题：regex

Yes I know its usually a bad idea to parse HTML using RegEx, but that aside can someone explain the fault here:

 string outputString = Regex.Replace(inputString, @"<?(?i:script|embed|object|frameset|frame|iframe|metalink|style|ht开发者_如何学Goml|img|layer|ilayer|meta|applet)(.|\n)*?>", "");
if (outputString != inputString)
{
   Console.WriteLine("unwanted tags detected");
}

It certainly detects the intended tags like: <script> and <html>, but it also rejects strings I want to allow such as <B>Description</B> and <A href="http://www.mylink.com/index.html">A Link containing 'HTML'</A>

I think the problem is the first question mark in

<?(?i:script

You probably want to match the leading "/" character in a closing html-tag, right? I think the question mark makes the "<" optional (zero or one match).

I suggest using

<(/)?(?i:script

but I am no RegEx-expert...

i am not sure how you do this in C# but it seems that you forgot to make your regexp case insensitive.

From what I see it just need a little nudge:

Change from

"<?(?i:script|...|applet)(.|\n)*?>"

"\<(?i:script|...|applet)(.|\n)*?\>"

As the characters < and > are special

I would change

"<?(?i:script|...|meta|applet)(.|\n)*?>"

"</?(?:script|...|meta|applet)[^>]*>"

I am not totally familiar with Javascript Regex strings, but I do have a reference and I am familiar with regex basics (and once in a while I need a refresher).

the \s is entirely optional - it is not needed. you can keep it in if you wish. note that this does NOT handle uppercase tags. you will need to handle those as additional cases.

you may have to escape the / in the string. you don't need a ? after the * because * means 0 to many, so that covers optional.

I am not sure, but I don't think the greedy * will overtake the (?:).

http://www.regular-expressions.info/quickstart.html