I want to:
1) count the number of round brackets '(', I expect as result 2
2) get the text inside, I expect "\"Happy"\", which appear in console output as "Happy"
No idea for 1. I try the following for 2
string k = Regex.Match(s1,@"\((\w+)\)").Groups.Value;
But It fails in understanding the \" character
You don't seem to be allowing any content between the <a> and </a>. I think you need (.*) in there (it should be a replacement group because it's what you want to keep), and the matching to be done non-greedily.
Also, you don't allow for multiple <a> inside the same <pre>.
I don't really think regex is the right tool for this job, as there's lots of context and state-change in what you're trying to do. An XML based solution seems better to me. But something like
... in non-greedy mode and writing all the found groups into the output might work.