Regular expression to remove <br> from <pre>

Question

I am trying to remove the <br /> tags that appear in between the <pre></pre> tags. My string looks like

string str = "Test<br/><pre><br/>Test<br/></pre><br/>Test<br/>---<br/>Test<br/><pre><br/>Test<br/></pre><br/>Test"

string temp = "`##`";
while (Regex.IsMatch(result, @"\<pre\>(.*?)\<br\>(.*?)\</pre\>", RegexOptions.IgnoreCase))
{
    result = System.Text.RegularExpressions.Regex.Replace(result, @"\<pre\>(.*?)\<br\>(.*?)\</pre\>", "<pre>$1" + temp + "$2</pre>", RegexOptions.IgnoreCase);
}
str = str.Replace(temp, System.Environment.NewLine);

But this replaces all <br> tags between first and the last <pre> in the whole text. Thus my final outcome is:

str = "Test<br/><pre>\r\nTest\r\n</pre>\r\nTest\r\n---\r\nTest\r\n<pre>\r\nTest\r\n</pre><br/>Test"

I expect my outcome to be

str = "Test<br/><pre>\r\nTest\r\n</pre><br/>Test<br/>---<br/>Test<br/><pre>\r\nTest\r\n</pre><br/>Test"

Answer 1

If you are parsing whole HTML pages, RegEx is not a good choice - see here for a good demonstration of why.

Use an HTML parser such as the HTML Agility Pack for this kind of work. It also works with fragments like the one you posted.