Regex options matching multi-line as well as ignoring the case

Question

I have some piece of ill-formed html, sometimes the " is missing. Also, it sometimes shows capital cases while other times lower cases:

<DIV class="main">
    <DIV class="subsection1">
   <H2>
   <DIV class=subwithoutquote>StackOverflow</DIV></H2></DIV></DIV>

I would like to match both multi-line and ignoring the case. But the following patern does not seem to be working. (For the concatenation, I also tried | instead of &)

const string pattern = @"<div class=""?main""?><div class=""?subsection1""?><h2><div class=""?subwithoutquote""?>(.+?)</div>";
Match m = Regex.Match(html, pattern, RegexOptions.IgnoreCase & RegexOptions.Singleline);

Or should I add \n* in the pattern to solve multi-line issue?

I have edited your title. Please see, "[Should questions include “tags” in their titles?](http://meta.stackexchange.com/questions/19190/)", where the consensus is "no, they should not". — John Saunders, Jan 30 '13 at 18:52
See http://stackoverflow.com/questions/1732348/regex-match-open-tags-except-xhtml-self-contained-tags — abatishchev, Jan 30 '13 at 18:53
Your regex fails, since you didn't allow free whitespace between the tags `\s+`. — nhahtdh, Jan 30 '13 at 18:57

score 7 · Accepted Answer · edited Sep 20 '17 at 06:35

The first problem is that you are not allowing for white-space in your regex between tabs. The correct regex (tested in Rubular) is:

<div class=""?main""?>\s*<div class=""?subsection1""?>\s*<h2>\s*<div class=\"?subwithoutquote\"?>(.+?)<\/div>\s*

Notice the addition of several \s* entries.

The second problem is that you're not concatenating the options properly.

Your code:

Match m = Regex.Match(html, pattern, RegexOptions.IgnoreCase & RegexOptions.Singleline);

Since these are bit flags, Bitwise-And (& operator) is a wrong flag. What you want is Bitwise-Or (| operator).

Bitwise-And means "if the bit is set in both of these, leave it set; otherwise, unset it. You need Bitwise-Or, which means "if the bit is set in either of these, set it; otherwise, unset it."

I've edited my original post. I tried both & and | neither worked. — Yang, Jan 30 '13 at 18:55
@Yang I've updated and corrected the regex ommission of whitespace, which fixes the problem. — ashes999, Jan 30 '13 at 19:57

Kyle C · Answer 2 · 2013-01-30T20:25:04.083

You need to OR them together in this case.

const string pattern = @"<div class=""?main""?><div class=""?subsection1""?><h2><div class=""?subwithoutquote""?>(.+?)</div>";
Match m = Regex.Match(html, pattern, RegexOptions.IgnoreCase | RegexOptions.Singleline)

Edit: Change your RegEx to the following ...

const string pattern = @"<div class="?main"?>\s*<div class="?subsection1"?>\*+<h2>\s*<div class="?subwithoutquote"?>(.+?)</div>

Regex options matching multi-line as well as ignoring the case

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