i want to capture all tags not having a specific tag

Question

i want to capture all tags named 'STRONG' i can use <STRONG.*?</STRONG> this is working just fine but i dont want to capture these tags if the 'SPAN' tags come in these tags i want something like <STRONG.*(^(SPAN)).*?</STRONG> this is the sample text

<STRONG> For technical <SPAN id=PageBreak>101</SPAN> please</STRONG>
<SPAN id=PageBreak type="4">56</SPAN><STRONG> visit</STRONG>

i want to capture the second strong tag and not the first one

Answer 1

You're trying to parse HTML structure using a regular expression, which is doomed to fail since the HTML language isn't regular (see hierarchy of formal languages).

Use an HTML parser instead, e.g. the HTML Agility Pack. See also these other questions.

Answer 2

Konrad is right.

But in case you don't care about imminent doom you could try something like

/<STRONG>\w+?<\/STRONG>/

Which will ignore STRONG tags if they enclose anything that isn't a word character, such as the '<' of '<SPAN>', but will no doubt fail for anything out of the ordinary...leading back to the point about a doomed attempt.

Answer 3

This is a typical use case for XPath. The query could be for example:

**/strong[not(child::span)]/text()

Answer 4

If you just want to know in general how to match text that doesn't contain a certain sequence of characters, here's the most common way:

Regex re = new Regex(@"<STRONG(?:(?!<SPAN).)*?</STRONG>",
    RegexOptions.IgnoreCase | RegexOptions.Singleline);