C＃正则表达可能被引号括起来的单词

Question

For a C# program I'm writing, I'm using regular expressions to look for a specific pattern and this pattern may or may not be surrounded by parentheses, but, if it is, I want to include them in the match.

So for example, say my pattern was just the word "hello" , I created this regex:

"\(?hello\)?"

But that doesn't take into account that the word must have BOTH opening and closing parentheses in order to qualify as a match. So, for example, if my search string was:

hello, (hello), (hello, my name is bob), (bob said hello)

What I would want would be to have the following 4 matches - hello , (hello) hello , hello

Specifically, the second match includes the parentheses, but the 3rd and 4th matches do not include any parentheses since they are not at the beginning AND the ending of the "hello".

What kind of regex could I use to accomplish this?

Answer 1

You could simply use an alternation to match \\(hello\\) or hello :

\(hello\)|hello

Since regular expressions are inherently greedy, (hello) will be match before hello which means that all four of the instances would be matched.

Answer 2

Before anyone else spends too much time on this, I did find an answer (but if you have a better way, please do share!!!)

After some research, my final pattern has become:

(\()?hello(?(1)\))

That uses an optional capturing group and conditional backreferencing

Again, if anyone has a nicer solution, please do share, but, otherwise, hope this manages to help someone else in the future!